The Contours and Limits of Environmental Remediation Under the Treaty on the Prohibition of Nuclear Weapons

The entry into force of the Treaty on the Prohibition of Nuclear Weapons (TPNW) in January 2021 has sparked analysis of the so-called ‘positive obligations’ under Article 6, requiring states parties to address prior harm caused by the testing or use of nuclear weapons to both individuals and the environment. But although there has been much discussion of victim assistance under Article 6(1), there has been comparatively little assessment of the environmental remediation obligation under Article 6(2) that requires affected states to remediate areas contaminated by the past testing or use of nuclear weapons through ‘necessary and appropriate measures’. This article represents an attempt to begin filling this lacuna by considering various issues and questions concerning the scope and limits of the environmental remediation obligation established by Article 6(2). Specifically, this article identifies the geographical scope of application of Article 6(2) to illustrate precisely where TPNW parties’ remediation efforts should be applied, considers the meaning and underlying objectives of ‘remediation’ activities required by Article 6(2), and finally examines certain facets concerning the temporal dimension of the environmental remediation provision. Ultimately, this discussion aims to clarify the contours of the environmental remediation provision of the TPNW, and hopes to offer practical insight for states parties and encourage further consideration of the operationalisation of Article 6(2) in due course.


Introduction
The vast number of nuclear weapon explosions during the twentieth century, principally from the testing but also the two known uses of nuclear weapons over Hiroshima and Nagasaki in August 1945, have caused significant environmental damage and contamination at various locations. From Pacific atolls to the former Soviet nuclear test site in Semipalatinsk, environmental damage caused by nuclear explosions has been well-documented, 1 though the lingering types of harms themselves have not been subject to any specific international regulation. Likewise, the recent illegal military invasion of Ukraine by Russia since February 2022, 2 particularly Vladimir Putin's decision to put Russia's nuclear weapons on 'high alert' on 27 February 2022, 3 has also raised fears of potential nuclear escalation, which would almost certainly result in devastating environmental effects.
Although there has been renewed attention paid to environmental protection during armed conflicts, 4 illustrated by the International Law Commission's (ILC) ongoing work on the Protection of the Environment in Relation to Armed Conflicts since 2011 resulting in the adoption of 28 Draft Principles in June 2019, 5 this has largely focused on developing principles to minimise environmental harm as a consequence of warfare. While the ILC Draft Principles do encourage cooperation amongst relevant actors 'with respect to post-armed conflict environmental assessments and remediation measures', 6 and address remnants of war that may cause harm to the environment 7 it is worth noting that nuclear weapons testing, by far the most common source of nuclear detonations, have occurred in 'peacetime'-or at the very least, outside of conflict situations covered by the Draft Principles. 8 Although future use of nuclear weapons during armed conflict cannot be ruled out-as the aforementioned Russian actions in Ukraine attest to-thereby potentially making the ILC Draft Principles relevant in the future, it remains the case that efforts to address environmental contamination and harm caused by the use and testing of nuclear weapons in peacetime are limited.
The adoption of the Treaty on the Prohibition of Nuclear Weapons (TPNW) 9 in 2017 offers a means to address this lacuna. As of 28 April 2022, the TPNW has been ratified by 60 states. 10 In accordance with Article 15(1), 11 the TPNW entered into force on 22 January 2021, 90-days after Honduras deposited the 50th instrument ratification to the UN Secretary-General. 12 The entry into force of the TPNW and the forthcoming first meeting of states parties (1MSP) scheduled to take place between 21 and 23 June 2022 13 marks the beginning of efforts by states parties, civil society, international organisations, and other stakeholders to operationalise the provisions of the treaty. Although not all of the provisions of the TPNW will take effect immediately, such as the Article 4 nuclear disarmament obligations that establish ways in which the nuclear weapon possessing states (NWPS) can accede to the TPNW, 14 one important set of obligations that are now operational are the so-called 'positive obligations' of the TPNW contained in Article 6, titled 'Victim Assistance and Environmental Remediation'. In brief, Article 6 entails a remedial function by requiring states parties to take affirmative action to address existing harms and damage to both affected individuals and the environment caused by the testing or use of nuclear weapons. 15 Although Article 6 does not reflect customary international law, and thus only binds states parties and applies to certain geographical areas of the world, 16 it nonetheless constitutes a 'groundbreaking' 17 provision within nuclear weapons law.
Much scholarship and interest thus far has centered around Article 6(1) concerning the provision of assistance to 'victims', or more accurately 'individuals affected by the testing or use of nuclear weapons '. 18 With this in mind, this article seeks to complement this important research, and aims to encourage further debate and thought surrounding the nature and scope of the environmental remediation obligation established by Article 6(2). In full, Article 6(2) reads: Each State Party, with respect to areas under its jurisdiction or control contaminated as a result of activities related to the testing or use of nuclear weapons or other nuclear explosive devices, shall take necessary and appropriate measures towards the environmental remediation of areas so contaminated.
This article undertakes an examination of the scope and limits of the environmental remediation obligation under Article 6(2). In essence, the following discussion identifies certain issues and questions surrounding the scope of various aspects of Article 6(2) that require further elaboration to bring clarity as to the overall nature and contours of environmental remediation under the TPNW, while advancing normative justifications for these identified limits. Ultimately, it is hoped that the analysis presented will pave the way for subsequent discussion and consideration of Article 6(2) both academically-similar to the broad literature that exists surrounding Article 6(1) of the TPNW on victim assistance 19 -while also providing valuable insights to state parties as implementation of Article 6(2) proceeds in the coming months and years.
Following this introduction, Sect. 2 provides a detailed account of how concerns over the environmental impact of nuclear weapons testing or use took hold during the 'Humanitarian Initiative' process and the 2017 United Nations (UN) Conference to Negotiate a Legally Binding Instrument to Prohibit Nuclear Weapons, Leading Towards Their Total Elimination . This section builds upon, and develops, existing scholarship 20 that has examined the development of positive obligations within existing 'humanitarian disarmament' agreements by focusing exclusively on how the environmental remediation provision in Article 6(2) emerged in the TPNW context. Section 3 considers the geographical areas to which the remediation obligations and measures under Article 6(2) shall be applied, by first noting how responsibility for implementation is allocated amongst TPNW parties before considering the geographical application of remediation measures within such allocated states. Section 4 discusses the nature of the obligation imposed upon TPNW parties by highlighting the meaning, objectives, and limits of 'remediation' efforts in the context of Article 6(2). It will be suggested that the concept of 'remediation' embraces a justifiably limited concept that imposes a less onerous obligation upon affected TPNW parties. Section 5 considers the temporal dimensions of remediation efforts under Article 6(2), first to emphasise the ability of Article 6(2) to address past and future contamination caused by the testing and use of nuclear weapons; and second, to illustrate the long-term nature of remediation efforts based on the absence of any pre-determined deadlines to 'achieve' remediation. Section 6 briefly concludes.

Incorporating Concerns for the Environment in the TPNW
As noted, this initial section provides a detailed overview of how environmental considerations ultimately came to influence the development of the environmental remediation obligation contained within Article 6(2) of the TPNW. Not only will this provide important context that complements existing research on the development of positive obligations in humanitarian disarmament treaties, 21 but such 21 Ibid. 19 Singh (2020); Docherty (2021a); Camins (2021). 20 See e.g., ; Bolton and Minor (2020), pp. 71-85. information supports discussion and analysis of how Article 6(2) should be interpreted and perceived both in the context of the present article, and for future scholarship and discussions of environmental remediation as implementation of the TPNW proceeds.

Highlighting Environmental Concerns During the 'Humanitarian Initiative'
The extent of environmental damage resulting from the use and testing of nuclear weapons has been documented elsewhere, and will not be elaborated upon in detail here. 22 Generally speaking, the initial detonation of a nuclear weapon during the 'blast phase' can incinerate the immediately proximate environment with temperatures reaching similar levels to that of the Sun, 23 destroying flora, fauna and agricultural lands, alongside local wildlife. 24 Furthermore, the radioactive fallout from specific instances of nuclear weapon use or testing can be lifted high into the atmosphere and dispersed over vast areas. Indeed, a 2000 UN Scientific Committee Report on the Effects of Atomic Radiation noted that atmospheric nuclear testing was the primary cause of 'unrestrained release into the environment of substantial quantities of radioactive materials, which were widely dispersed in the atmosphere and deposited everywhere on the Earth's surface ' between 1945 and 1980, 25 resulting in extensive environmental contamination of vegetation, water sources, and wildlife, much of which may last for decades. 26 This awareness of the environmental legacy of nuclear weapons testing, along with extensive knowledge of the human impact of nuclear weapons detonations from a health perspective 27 and the disproportionate gendered effects of radiation exposure, 28 served as vital inspiration for the 'Humanitarian Initiative' that informed the TPNW process. Notably, the convening of three 'Humanitarian Conferences' in Oslo, Nayarit, and Vienna between March 2013 and December 2014 provided space to elaborate upon the environmental impact of nuclear weapons detonations further. 29 For example, at the Oslo Conference in 2013, Ira Helfand of the International Physicians for the Prevention of Nuclear War discussed the varying nature of environmental damage that would result from the future detonation of nuclear weapons depending upon weather conditions and other variables. 30 During the Vienna Conference in 2014, scientists brought attention to the potential atmospheric and climate 22 See e.g., Prăvălie (2014);Unal et al. (2017); Alexis-Martin et al. (2021). 23 Koppe (2009), pp. 61-87. 24 See e.g. the testimonies collated by Alexis-Martin et al. (2021), pp. 113-114. 25 United Nations Scientific Committee on the Effects of Atomic Radiation, Report to the General Assembly, UN Doc. A/55/46, 2000, Vol. I, pp. 4-5. 26 Unal et al. (2017 See e.g. Borrie (2014); Maresca and Mitchell (2015), pp. 623-626. 28 Venturini (2019), p. 99;Borrie et al. (2016). 29 For a discussion of the conferences, see Minor (2015); Kmentt (2015). Statements and presentations can be found at Reaching Critical Will, Humanitarian Impact of Nuclear Weapons. https:// www. reach ingcr itica lwill. org/ disar mament-fora/ hinw. Accessed 28 Apr 2022. 30 Helfand (2013). impacts caused by a 'nuclear winter' following a limited nuclear exchange, resulting in a significant drop in global temperatures and impacting agricultural production and food-security worldwide. 31 Others sought to emphasise the environmental and health impacts caused by past nuclear weapons testing and production. 32 However, it was during the 2016 Open-Ended Working Group (OEWG) established pursuant to UN General Assembly (UNGA) Resolution 70/33 33 that states began to advance more fully formed positions regarding the inclusion of positive obligations-including commitments to remediate damaged environments-as one of the possible elements of a proposed ban treaty. Notably, Fiji, Nauru, Palau, Samoa, and Tuvalu-states located in the heavily affected Pacific region-jointly suggested that central to a ban treaty would be the incorporation of 'obligations to provide assistance to victims' and 'to address damage to the environment'. 34 Similarly, civil society groups including both the International Campaign to Abolish Nuclear Weapons (ICAN) 35 and Article 36 emphasised the importance of including positive obligations to 'address damage to affected environments' in any instrument designed to prohibit and eliminate nuclear weapons. 36 Ultimately, as well as recommending the convening of the 2017 Conference by the UNGA, 37 the Final Report of the OEWG published in September 2016 expressly noted that: Possible elements of such an instrument could include… (f) recognition of the rights of victims of the use and testing of nuclear weapons and a commitment to provide assistance to victims and to environmental remediation. 38

Progress in the Negotiations?
Despite the adoption of this brief, though highly important, paragraph, various commentators have observed that there was a degree of hesitancy amongst participating states and even some civil society activists as to whether positive obligations should be included in the negotiated treaty. 39 Bolton and Minor (2020), pp. 71-85. the mandate of the 2017 Conference did not explicitly mention the need to negotiate or include positive obligations in any final text. 40 Furthermore, this 'lack of enthusiasm' 41 was reflected in the provisional agenda for the March 2017 session, where no specific discussion topic on positive obligations was included by states. 42 Ultimately, to overcome this hesitancy, environmental remediation was presented by its proponents to state participants as a 'different type of clearance' obligations previously contained in existing humanitarian disarmament agreements, notably the Anti-Personnel Mine Ban Convention (APMBC) 1997 43 and the Convention on Cluster Munitions (CCM) 2008, 44 adapted to address the unique harms stemming from nuclear weapons-related remnants and radioactive contamination. 45 In addition, supporters of including positive obligations in the TPNW emphasised the need to avoid 'stepping backwards' from the precedent set by the positive obligations included within earlier humanitarian disarmament instruments. For example, in an editorial comment published in Reaching Critical Will's 'Nuclear Ban Daily' reports on the TPNW negotiations in March 2017, Docherty argued that: states negotiating the nuclear weapons ban should ensure that the new treaty does not represent a regression for humanitarian disarmament in any way… a failure to include positive obligations alongside those prohibitions would represent a step backward from current disarmament norms. 46 This rationale proved successful, and as the March 2017 session progressed, certain civil society groups including Article 36, 47 ICAN, 48 and states, notably Papua New Guinea, presented formal working papers outlining how positive obligations could be included and formulated within the final text, including a focus on environmental remediation. 49 According to representatives of Pace University International Disarmament Institute, '16 states plus CARICOM 50 expressed support in 46 Docherty (2017), p. 5. See also Minor (2017 Bolton and Minor (2020), p. 71. 50 CARICOM, or the Caribbean Community of States, is a group of 15 member states and five associated states located in the Caribbean that promotes economic integration and foreign policy coordination amongst its members. See usefully, CARICOM, Who We Are, https:// caric om. org/ our-commu nity/ whowe-are/. Accessed 28 Apr 2022. their statements for environmental remediation of areas contaminated by the use (including testing) of nuclear weapons' 51 -though only in a rather unelaborated manner. 52 With this increased level of support, conference President Elayne Whyte Gómez decided to include victim assistance and environmental remediation provisions within Article 6 of the 22 May first draft treaty text. 53 However, despite getting the positive obligations through the door, the initial draft Article 6(2) was relatively toothless, and merely afforded affected states a 'right to request and to receive assistance toward the environmental remediation of areas so contaminated', rather than imposing a specific obligations upon state parties to take affirmative action to address environmental damage.
Moving to the June-July session, civil society groups sought to strengthen the positive obligations considerably. Mines Action Canada, for example, argued that '[t]he language should be amended to make clear that state parties have an obligation to take necessary and appropriate measures to ensure remediation of contaminated areas under their jurisdiction or control'. 54 ICAN adopted a similar stance. 55 The International Committee of the Red Cross (ICRC) proposed the following formulation: Each State Party with respect to areas under its jurisdiction or control contaminated as a result of activities related to the testing or use of nuclear weapons or other nuclear explosive devices, shall take necessary and appropriate measures towards the environmental remediation of areas so contaminated. 56 Furthermore, a specific agenda topic on 'Positive Obligations' was included in the agenda of the June-July session, facilitated by Chilean Ambassador Alfredo Labbé. 57  rewarded as the discussion group led by Ambassador Labbé delivered agreed upon revised wording that strengthened the environmental remediation provision in line with the ICRC's proposal. 58 These recommendations were collated by President Whyte Gómez into a draft distributed on 3rd July 2017, 59 and remained unchanged through to the end of the negotiations.

Geographical Limits
Having provided a detailed summary of how environmental obligation came to be included in the TPNW in the first place, the remainder of this article seeks to explore certain characteristics and elements of the environmental remediation obligation established by the Article 6(2) in order to elucidate the overall scope of the provision. A variety of perspectives will be considered, each of which seeks to consider the limits and boundaries of Article 6(2) in a holistic fashion.
As a first port of call, a particularly interesting limiting factor relating to the environmental remediation obligation concerns the geographical areas to which the obligation and remediation measures adopted pursuant to Article 6(2) will apply. Indeed, while it is apparent that Article 6(2) seeks to address environmental contamination caused by the testing and use of nuclear weapons, such contamination does not exist within a vacuum but is instead located within a physical, geographical space on earth. With this in mind, determining the geographical scope of Article 6(2) revolves around two related issues; first, to consider how the TPNW allocates responsibility for implementing Article 6(2) amongst its states parties; and second, to what geographical 'space' or areas does the obligation and the remediation measures required under Article 6(2) apply to within these allocated states. In other words, one must clarify which states are obligated under Article 6(2), and precisely where such obligation should be applied on the ground by these very states. Each of these issues will be explored in turn.

Allocation of Responsibility for Implementing Article 6(2)
A first, though important question here concerns to which TPNW state parties the obligation under Article 6(2) applies to. This is a topic that has received some scholarly attention elsewhere that will be drawn upon in the following analysis, 60 and effectively revolved around the issue of determining which states under the TPNW should have primary responsibility for the implementation of Article 6. Generally 58 Amendments to Draft Articles 6-8, 2017 Conference, 30 June 2017, https:// reach ingcr itica lwill. org/ images/ docum ents/ Disar mament-fora/ nucle ar-weapon-ban/ docum ents/ Artic les-6-8-30-June. pdf. On the one hand, it was strongly recommended by civil society groups, 61 including ICAN and the ICRC, that that primary responsibility for the implementation of Article 6 should rest upon those states parties that were 'affected' by the testing or use of nuclear weapons, as opposed to the 'user' states. 62 This would have effectively followed the precedent set by both the APMBC and CCM, each of which place responsibility for the implementation of clearance of unexploded conventional remnants upon the affected territorial state, as opposed to the state that actually used the anti-personnel mines or cluster munitions. 63 On the other hand, a number of states including Cuba, 64 Egypt, 65 Malaysia, 66 Thailand,67 and Vietnam,68 amongst others, endorsed the inclusion of a 'polluter pays' allocation of responsibility in relation to the implementation of Article 6. 69 The would have drawn upon the development of the polluter pays principle within international environmental law that emerged during the 1970s by the Organisation for Economic Co-operation and Development, 70 which allocates the 'costs' of environmentally damaging acts to those states that have caused the damage or pollution in question. 71 If applied in the context of Article 6 of the TPNW, a polluter pays-style approach would have essentially imposed primary responsibility on those states that had 'used' or 'tested' nuclear weapons to engage in the remedial measures-in other words the NWPS. 72 In the end, the TPNW incorporated a blended approach to responsibility in the context of both environmental remediation and victim assistance. 73 To begin, and drawing heavily from the recommendations of civil society 74 and the ICRC, 75 Article 6(2) places primary responsibility in the hands of state parties affected by prior nuclear weapon testing or use, to take necessary and appropriate steps towards environmental remediation 'with respect to areas under its jurisdiction or control'. In other words, Article 6(2) confirms that each TPNW party is primarily responsible for addressing contamination caused by the testing or use of nuclear weapons that 'it' may have within its 'jurisdiction or control'. 76 The imposition of affected state responsibility under Article 6(2) has been criticised for imposing a potentially undue burden upon states parties, 77 the majority of which did not in fact use or test nuclear weapons that caused the harm in question. 78 Moreover, such 'affected' state parties may lack the economic or technical resources to implement 'necessary and appropriate' remediation measures pursuant to Article 6(2). Casey-Maslen makes a similar point and suggests that '[w]hether a heavily affected state, such as the Marshall Islands, will be able to "adequately provide" assistance' under Article 6(1) is unclear, 79 a point that may logically extend to its ability to provide 'necessary and appropriate measures' for environmental remediation in Article 6(2).
At the same time, this designation of affected state responsibility reflects the approach adopted by Article 5(1) of the CCM, and has been justified from its proponents, such as the International Human Rights Clinic (IHRC) at Harvard Law School, which argues that it 'respects the affected state's sovereignty… [and] … recognizes that the affected state is in the best position to assist because it has a more in-depth understanding of the problem and easier access than other states parties to its people'. 80 Moreover, given the opposition of the NWPS to the TPNW process, this approach allows Article 6 to become immediately operational following the entry into force of the TPNW in January 2021. 81 Finally, the TPNW does allude to a collective sense of responsibility when implementing the positive obligations under Article 6, 82 including amongst others, 83 Article 7(3) which establishes an obligation upon unaffected state parties 'in a position to do so' to provide 'technical, material 76 This phrase jurisdiction or control will be considered next and concerns the geographical extent of each TPNW party's jurisdictional limits, see Sect. 3.2. 77 Rietiker argues that the imposition of primary responsibility is 'regrettable since many States affected by testing of nuclear weapons might not be in a position to fulfil their obligations under Article 6(1), and (2)', see Rietiker (2017) Doggett and Osman (2017), p. 2. New Zealand also argued that setting primary responsibility to user or testing states would mean that the implementation of Art. 6(2) would be 'illusory', New Zealand, 26th mtg 2017 Conference, 5 July 2017, https:// media. un. org/ en/ asset/ k1y/ k1y8b iadz8. Accessed 28 Apr 2022. 82  and financial assistance to State Parties affected by nuclear-weapons testing or use, to further the implementation of this Treaty'. 84 Additionally, Article 7(6) attempts to attribute some form of responsibility for victim assistance and environmental remediation on states that have either tested or used nuclear weapons, 85 though this will remain unimplemented for so long as those user and testing states continue to oppose and remain outside of the TPNW regime.
More significantly, however, at least for present purposes is the question, which states would actually constitute or fall within the ambit 'affected states parties' obligated by Article 6(2)? There are two general classes of affected states that can be identified. First, and most obviously an affected state party obligated under Article 6(2) would almost certainly include any state where the testing or use of nuclear weapons has taken place. This seems uncontroversial. Indeed, given the long-lasting nature of environmental harms, 86 it will be the case that states where past testing took place will continue to suffer at least some form of lingering environmental contamination. Amongst current TPNW parties, as of 28 April 2022, this would include Kazakhstan and Kiribati, along with Algeria as a current signatory. 87 However, the notion of affected states could extend beyond the states where nuclear weapons testing actually occurred, particularly because fallout and contamination may extend beyond the affected state where the testing occurred and impact other geographically proximate 'third' states too. For example, monitoring stations established by New Zealand in the 1960s and 70s in other Pacific countries including Fiji, Niue, Tonga, Samoa and Tuvalu detected radioactive fallout from French testing at sites in French Polynesia, including in milk samples that contained high concentrations of Iodine-131. 88 In fact, it was such concerns over the environmental impact and fallout of atmospheric nuclear testing by France in the Pacific during the 1970s that led to Australia and New Zealand bringing claims to the International Court of Justice (ICJ or 'the Court) in the Nuclear Test Cases in 1973. 89 Given the language of Article 6(2), these 'third' states impacted by fallout would also be classed as 'affected' states for the purposes of environmental remediation under the TPNW. Indeed, there is no requirement within Article 6(2) that only the state where the testing or of nuclear weapons use occurred should undertake positive remedial steps. Rather, Article 6(2) operates based upon the presence of contamination within areas under an affected state's 'jurisdiction or control'. 84 See usefully Docherty (2018)

Geographical Application Within an Affected States' 'Jurisdiction or Control'
Having illustrated that the TPNW imposes primary responsibility for the implementation of Article 6(2) upon affected states parties, Article 6(2) requires such affected states to implement necessary and appropriate environmental remediation measures to address contamination caused by the testing or use of nuclear weapons within 'areas under its jurisdiction or control'. It is this latter phrase that will be considered now in determining the geographical reach of an affected states obligations pursuant to Article 6(2).
First, it is worth noting that the use of language concerning the geographical application of obligations assumed under the TPNW, including Article 6(2), is not entirely consistent. For example, at times the treaty employs the phrase 'territory or at any place under its jurisdiction or control' in relation to the Article 1 prohibitions on the stationing, installation and deployment of nuclear weapons, 90 the Article 2 declarations concerning the presence of host states weapons, removal of stationed nuclear weapons under Article 4(4), and the national implementation of obligations accepted by states under the TPNW. 91 Accordingly, the fact that only the phrase 'jurisdiction or control' is used within Article 6(2), thus omitting the term territory, raises the initial question as to whether the scope of this provision's application is limited geographically at all. This seems unlikely. Although the TPNW does not define the terms 'territory' or 'jurisdiction or control', there is a degree of overlap between these concepts. Beginning with the term 'control', Casey-Maslen in discussing Article 5 of the TPNW concerning national implementation, argues this notion of control 'refers primarily to foreign territory that is occupied by the state party but which is not part of a state's sovereign territory'. 92 Equally, this could cover land controlled by a state under a territorial lease arrangement that has some form of contamination caused by nuclear weapons testing or use. 93 This additional term therefore expands the scope of an affected state's obligation under Article 6(2) extraterritorially beyond its own borders to additional locations over which the affected state in question exercises some form of de facto rather than de jure control. 94 Such situations will likely be less frequent in occurrence, but should not be ruled out entirely.
Turning to the term 'jurisdiction' as included within Article 6(2), this describes the competence of states, in exercising their sovereignty, to both prescribe and to enforce created laws upon persons and property under its municipal law. 95 Significantly, a state's ability to exercise its jurisdiction operates primarily (though not exclusively) with respect to its own territory, 96 notwithstanding the nationality 90 TPNW, Art. 1(1)(g). 91 Ibid., Art. 5(2). 92 Casey-Maslen (2019), p. 206. 93 See for territorial leases, Strauss (2007). 94 See also Aust (2013), pp. 179-182. 95 Ryngaert (2015), p. 9. 96 Mills (2014), p. 196;Klabbers (2021), p. 101. See also Arbiter Max Huber in Island of Palmas (US v. The Netherlands), 2 RIAA, 1928, 829, p. 838;and Bankovic et al. v. Belgium et al., App. No. 52207/99, 2001, ECHR 890, para. 5. principle of state jurisdiction which is of less immediate relevance here, 97 and the extraterritorial application of jurisdiction. 98 Accordingly, states are said to enjoy plenary jurisdiction within their sovereign territory, 99 confirming in principle that a state is able to exercise jurisdiction over all persons and activities within its territorial boundaries. 100 With this in mind, it seems apparent that for affected states parties implementing Article 6(2), the application of remediation measures to 'areas under its jurisdiction or control contaminated as a result of activities related to the testing or use of nuclear weapons' essentially correlates to the affected state's territory.
What then constitutes an affected state's 'territory' for the purposes of determining the geographical application of Article 6(2) to areas within the jurisdiction or control of an affected state party? Although the TPNW does not define the notion of 'territory', it is a concept that has a fairly determinable meaning within international law. Ordinarily, an affected state's territory reflects its land masses and the air space above, though the ICJ has emphasised that the territorial borders of the state do not necessarily have to be clearly delineated or set in stone in meeting the criteria for statehood. 101 Furthermore, it is clear that a state's territory includes its internal waters, including bays, estuaries, 'internal seas', and lagoons, 102 while also extending to the 12 nautical mile 'territorial sea' of a coastal state too permitted by the United Nations Convention on the Law of the Sea (UNCLOS) 1982, 103 and now accepted under customary international law. 104 It would seem that this common understanding of a state's territorial limits would seem appropriate to adopt in the present context of Article 6(2) of the TPNW. Indeed, adopting this approach to territory based on jurisdiction would reflect existing approaches to delineating a state's territorial limits within existing international law. Furthermore, it is worth noting that a comparable understanding definition of 'territory' has been adopted in other nuclear weapons-related treaties, notably the South Pacific Nuclear-Free Zone Treaty 1985, which under Article 1(b), defines territory as 'internal waters, territorial sea and archipelagic waters, the seabed and subsoil beneath, the land territory and the airspace above them'. 105 Accordingly, departing from the common accepted understanding of territory under general international law, over which state parties to the TPNW exercise jurisdiction or control 97 See Staker (2018) would seem unwarranted in the absence of a contrary definition within the treaty text.
It is also apparent that this understanding of territory over which TPNW parties exercise jurisdiction would prove useful from a practical perspective and would ensure that the remediation obligation within Article 6(2) would be applied to, and thus would address, radioactive materials and contamination that may still be present on the territorial seabed, internal waters and lagoons, or the wider marine environment at former nuclear test sites today. This would have particular relevance for atolls located in the Pacific within the jurisdiction of states parties such as Kiribati where testing took place both on land and offshore within territorial waters. 106 Indeed, a recent study has revealed that high levels of radioactive contaminants remain at the 'Castle Bravo' test crater located at Bikini Atoll in the Marshall Islands, 60 years after the nuclear weapon test took place by the US. 107 Accordingly, capturing internal waters, land masses, and the adjacent territorial sea within the notion of 'jurisdiction or control', as connected to territory, is vital for the successful operationalisation of Article 6(2).
At the same time, the standard definition of territory employed for the purposes of Article 6(2) is subject to appropriate limitations-again in line with existing international law-particularly by not extending an affected state's obligation under Article 6(2) past the 12 nautical mile territorial sea where, beyond this point, a state's 'territorial jurisdiction is gradually […] reduced, fading out with increasing distance form land territory, which forms the core space of the territorial state'. 108 Accordingly, the understanding of territory above pragmatically avoids extending the jurisdictional scope of the TPNW to cover exclusive economic zones (EEZ), an issue that has resulted in opposition from the NWPS in relation to signing the negative security assurance protocol of the Treaty on the Southeast Asia Nuclear Weapon-Free Zone's territorial area of application. 109 Here, jurisdiction is not strictly exercised on a territorial basis, but rather applies only to certain activities such as the exploration and exploitation of natural resources within the EEZ that extends up to 200 miles off the coastal states baseline. 110 Furthermore, this correctly avoids extending the jurisdiction of TPNW parties over the 'high seas', defined in Article 86 of UN CLOS, 111 which, as a geographical space at least, has consistently remained free from claims of sovereignty or appropriation by states 112 -notwithstanding continued 'flag state' jurisdiction over registered vessels on the high seas 113 -and must be used for 'peaceful purposes '. 114 Clearly, therefore, Article 6(2) requires all affected states parties to engage in 'necessary and appropriate' remediation measures to any contaminated area as a result of activities related to the testing or use of nuclear weapons that falls within its territorial jurisdiction, as defined above, or within any areas that it may exercise control other than through its exercise of jurisdiction. Such a conclusion is uncontroversial, and simply reflects the sovereignty of states to enact and enforce rules and international law obligations assumed, such as Article 6(2), over its territorial boundaries under international law. Indeed, it would be impossible to align a broader definition with the general understanding of jurisdiction and the sovereign equality of states under international law 115 and the principle of non-intervention, 116 but also the language of Article 6(2) itself which places responsibility on 'affected' states parties to engage in remediation with 'its' jurisdiction or control.
Equally, however, this conclusion regarding the limits of a state's territorial jurisdiction, and thus the geographical reach of Article 6(2), would suggest that radioactive contamination from the testing or use of nuclear weapons that is dispersed as fallout on beyond a state's 12 nautical mile territorial sea would remain unaddressed by Article 6(2) of the TPNW. This failure to cover contamination from the testing and use of nuclear weapons on the high seas would prima facie seem problematic, particularly so given that nuclear weapons testing on the high seas, both underwater and atmospheric, have been a major source of contamination of the oceans in the 20th Century. 117 Although Prăvălie notes that oceans have been able to assimilate radioactive particles from past nuclear testing to some degree, 118 and while ocean currents have dispersed radionuclides far beyond the original site of nuclear weapon tests thereby reducing the level of radioactive contamination to lesser concentrations, 119 this does not exclude the possibility that significant sources of radioactive contamination from nuclear testing may remain present at marine locations or within marine organisms in areas beyond the jurisdiction, control, and thus territory of TPNW parties, including on the seabed in deep ocean trenches. 120 Furthermore, the leaching of radioactive waste materials from past nuclear testing into the wider ocean either through leakage from waste storage facilities, such as the infamous 'Runit Dome' in the Marshall Islands, 121 or increased geological fragility at atolls in the Pacific continues to present a real, if 'difficult to asses', danger. 122 Simply put, future dispersion of lingering radioactive contamination from the testing of 115 Ryngaert (2015) (2019); See also Seo (2021), p. 102, noting in the context of radioactive waste, that such forms of pollution are not degradable and that there is no 'possibility of removing radioactivity from the sea once it has entered the water'. 121 Rust (2019). nuclear weapons into the marine environment beyond the jurisdiction or control of an affected TPNW party cannot be ruled out.

Addressing the Limited Spatial Reach of Article 6(2)
However, despite the geographical limitations of Article 6(2), it is suggested that other existing international frameworks can address nuclear weapons-related contamination in marine areas beyond the territorial jurisdiction of states. Notably, this could occur through the framework of Part XII of UNCLOS, 123 titled 'Protection and Preservation of the Marine Environment'. Part XII represents the 'foundation for the international environmental law of the seas', 124 and encapsulates an understanding that pollution is no longer an 'implicit freedom of the seas', but instead should be subject to diligent control. 125 It is beyond the scope of this article to examine Part XII in detail, 126 but certain aspects of the protection and preservation framework regime created by UNCLOS could complement the implementation of remediation efforts pursuant to Article 6(2) of the TPNW in areas beyond the jurisdiction of TPNW parties.
Although Part XII is centred around the protection and preservation of the marine environment, much of the UNCLOS framework is principally concerned with regulating 'pollution of the marine environment'. This is defined in Article 1(1)(4) of UNCLOS as: the introduction by man, directly or indirectly, of substances or energy into the marine environment, including estuaries, which results or is likely to result in such deleterious effects as harm to living resources and marine life, hazards to human health, hindrance to marine activities, including fishing and other legitimate uses of the sea, impairment of quality for use of sea water and reduction in amenities.
The term 'pollution' was given an intentionally wide meaning by the 1972 Group of Experts on the Scientific Aspects of Marine Environmental Protection in order to account for new sources of pollution of the marine environment that may arise in the future. 127 Harrison, for example, notes that this definition is 'broad in scope and applicable to all sources of pollution', including 'classic' contaminants such as sewage, petroleum, and, significantly, radionuclides. 128 Accordingly, it seems likely that radioactive contaminants released into marine environments following the testing or 123 See UNCLOS, Arts. 192-237. 124 Charney (1994) Seo (2021), p. 60, who notes that he definition of marine pollution in UNCLOS would capture Fukishima-treated radioactive wastewater. use of nuclear weapons would constitute 'pollution' within the meaning of Article 1(1)(4), provided that the level of such radiation concentrations are more than negligible, and pose harm to marine life. 129 Part XII of UNCLOS proceeds to establish a comprehensive framework of general rules for marine environment preservation and protection in  that are dynamic and flexible enough to evolve and be 'transposed to apply to other specific environments or the global environment as a whole'. 130 Article 192 imposes a general obligation upon states parties to 'protect and preserve the marine environment' without any qualification, 131 a provision that reflects customary international law. 132 This obligation is given further content by Article 194(1), which reads: States shall take, individually or jointly as appropriate, all measures consistent with this Convention that are necessary to prevent, reduce and control pollution of the marine environment from any source, using for this purpose the best practicable means at their disposal and in accordance with their capabilities, and they shall endeavour to harmonize their policies in this connection. Similar to Article 6(2) of the TPNW, the South China Sea Arbitration confirmed that Articles 192 and 194(1) of UNCLOS imposes a positive obligation upon states 'to take active measures to protect and preserve the marine environment' in order to maintain but improve its current condition, 133 principally by reducing and controlling 'pollution' from any source. Equally significant, however, is that the framework of obligations established by Part XII is applicable to all marine environments across all defined jurisdictional zones created by UNCLOS, thereby addressing marine pollution 'both inside the national jurisdiction of States and beyond it', including the high seas. 134 Straight away, therefore, one can see how the marine protection and preservation obligations established by Part XII of UNCLOS are broad enough to capture nuclear weapons testing-related contamination in marine environments outside of the territorial boundaries of states within its general scope.
Moreover, these general obligations are ultimately informed by other provisions of Part XII, alongside 'other applicable rules of international law'. 135 For example, Article 194(1) is elaborated upon in Section 5 of Part XII which grants states discretion to adopt rules and standard to address certain 'sources' of marine pollution in greater detail, 136 from land-based activities; seabed activities; activities in the 'Area'; dumping; vessels; and atmospheric pollution. 137 Furthermore, Article 197 creates a duty to cooperate in the implementation of the marine preservation and protection measures, which the tribunal in the MOX Plant Arbitration argued represents a 'fundamental principle in the prevention of pollution of the marine environment' under UNCLOS. 138 The importance of cooperation in implementation bears some similarity to the collective approach to implementation of Article 6 of the TPNW envisaged in Article 7, and endorsed by civil society. 139 Pursuant to this cooperation obligation under Article 197, UNCLOS parties are required to notify other states if they are in danger of marine pollution, 140 monitor the risks of marine pollution, 141 and publish results of research and studies undertaken towards this end. 142 States must also not address existing marine pollution by simply transferring such damage or pollution from one area to another or 'transform one type of pollution into another'. 143 These supplementary obligations ultimately help advance and give content to the general obligation in Article 194(1), but are also flexible and generalisable enough to be transferred or usefully applied to remediation efforts under Article 6(2) of the TPNW within the territorial limits of an affected state party.
Importantly, it should be borne in mind that although binding, Article 194(1) does not seek to prohibit or eliminate all pollution of the marine environment, 144 which may, in any case, be practically impossible. Rather, UNCLOS as a whole seeks to strike a balance between competing interests, from marine environment protection, to resource management and exploitation, 145 to navigational rights and so on. 146 With this in mind, Article 194(1) is generally interpreted as creating a due diligence obligation of conduct, rather than result, requiring a 'certain level of vigilance' in order to minimise pollution of the marine environment. 147 Moreover, because the financial, technological, and other material capabilities of states can differ substantially, as can the nature of different types of pollution, 148 UNCLOS parties are afforded some discretion to the 'best practicable means at their disposal' to prevent, reduce, and control pollution to remain in compliance with the general obligation within Article 194(1). 149 This indicates that UNCLOS parties, particularly developing states, will not have exactly the same level of responsibility in preventing, reducing, or controlling marine pollution. 150 Finally, although UNCLOS sets no specific targets or detailed standards that must be met in addressing pollution of the marine environment from different sources, 151 the framework nature of Part XII leaves the decision to create additional regulatory regimes to address specific sources of pollution up to its states parties. 152 In this sense, McConnell and Gold note that UNCLOS parties are encouraged to 'harmonize their legislation and practices both regionally and through international organizations and diplomatic conferences, globally'. 153 Indeed, Article 237 expressly recognises the complementary relationship between UNCLOS and other conventions addressing the protection and preservation of the marine environment in a more specific manner 'in furtherance of the general principles set forth' in UNCLOS. 154 With this observation in mind, and notwithstanding the limited geographical scope of Article 6(2) noted above, 155 this author suggests that the institutional settings and infrastructure of the TPNW established pursuant to Article 8 could provide a means for TPNW parties to develop specific measures to address marine pollution caused by the testing and use of nuclear weapons beyond the jurisdiction of states parties pursuant to the general obligations of Articles 192 and 194(1) of UNCLOS. Indeed, pursuant to Article 8(1) of the TPNW: States Parties shall meet regularly in order to consider and, where necessary, take decisions in respect of any matter with regard to the application or implementation of this Treaty, in accordance with its relevant provisions, and on further measures for nuclear disarmament, including: a The implementation and status of this Treaty;… c Any other matters pursuant to and consistent with the provisions of this Treaty.
Although somewhat simplified compared to earlier drafts, 156 this provision is non-exhaustive and permits a broad variety of issues to be discussed within such meetings provided that the issue is in regard to the 'application or implementation' of the TPNW, 157 or constitutes a matter that is 'pursuant to and consistent with the provisions' of the TPNW under Article 8(1)(c). Indeed, the phrase 'implementation and status of this treaty' employed in Article 8(1)(a) could be considered a 'catchall' term that allows the meeting to consider virtually any issue that relates to the TPNW. Comparable meetings of states parties pursuant to the APMBC and CCM have become 'major decision-making event[s]' that have transformed institutional settings within these disarmament treaties into dynamic processes for treaty development and implementation. 158 The TPNW, as the third example of the humanitarian disarmament movement, will likely follow suit in this regard.
Accordingly, it seems entirely plausible that the Article 8(1) meetings of states parties could permit TPNW parties to consider, and potentially adopt decisions regarding the extension of environmental remediation efforts beyond the territorial limits defined in Article 6(2). As the UNCLOS marine protection framework in Part XII is general in nature and thus requires additional development, discussing and perhaps adopting additional commitments or strategies within the institutional settings of the TPNW pursuant to Article 8 could help address the limited geographical reach of Article 6(2), coordinate states efforts in addressing marine pollution caused by the testing or use of nuclear weapons beyond any states jurisdiction, and ultimately provide specificity to the general marine protection goals enshrined in Articles 192 and 194(1) of UNCLOS. Indeed, one could see how such discussions and possible decisions to address contamination beyond the geographical limits of Article 6(2) into marine environments such as the high seas could constitute a matter that is in relation to the 'application and implementation' of remediation efforts under Article 6(2).
Admittedly, it is unlikely that the NWPS members of UNCLOS and their military aligned states would cooperate with any adopted marine protection measures developed within the TPNW institutional framework given their unequivocal opposition to the treaty since its adoption in 2017. 159 Equally, however, it is worth emphasising that such failure to engage with any supplementary obligations discussed within the framework of the TPNW would not absolve such TPNW-opposed states from abiding by their legally-binding, general marine protection obligations accepted under Article 192,Article 194(1), and Part XII generally of UNCLOS, 160  gov/ joint-press-state ment-from-the-perma nent-repre senta tives-to-the-united-natio ns-of-the-united-statesunited-kingd om-and-france-follo wing-the-adopt ion/. Accessed 28 Apr 2022; and amongst NATO members, Brussels Summit Communiqué, NATO, 14 June 2021, https:// www. nato. int/ cps/ en/ natohq/ news_ 185000. htm, para. 47. Accessed 28 Apr 2022. 160 Indeed, the tribunal in the South China Sea Arbitration ultimately held that China had breached Art. 192 and Art. 194(1) of UNCLOS, thus illustrating the binding and justiciable nature of these commitments, see South China Sea Arbitration (Merits), PCA, 2016, Case No. 2013 Indeed, it is generally accepted that many of the general obligations under Part XII of UNCLOS reflect customary international law, see Charney (1994), pp. 886-887;Sands and Peel (2012), p. 350. It is beyond the scope of this paper to explore fully the contribution of the UNCLOS framework in addressing nuclear weapons-related contamination of the marine environment beyond the jurisdiction or control of TPNW parties. Nevertheless, the fact that 167 states and the EU are parties to the UNCLOS 162 (and potentially all states given the customary status of these general provisions), and are explicitly required by these general obligations in Part XII to 'reduce and control' pollution to the entire marine environment to their best practicable means available illustrates prima facie how the general framework established by UNCLOS could provide an existing framework of commitments that can complement and perhaps address the limited geographical scope of Article 6(2) of the TPNW, at least to some degree. Whether this occurs through mechanisms developed within the auspices of the TPNW institutional settings under Article 8, or simply in implementing Part XII of UNCLOS generally, the limited geographical reach of remediation efforts under Article 6(2) of the TPNW should not be considered in isolation from the wider corpus of international law that address marine environmental protection.

The Meaning of Environmental Remediation
Another interesting issue that arises concerns the overall nature and scope of the objectives contained within Article 6(2). Indeed, although it is clear that this provision seeks to address environmental contamination caused by the testing or use of nuclear weapons, it remains necessary to clearly determine the overarching 'endgoal' and objectives behind the environmental remediation obligation in Article 6(2). Accordingly, this section seeks to determine the precise contours of the obligation imposed upon, and thus expected of, affected state parties implementing Article 6(2) by considering the underlying meaning and objectives of 'remediation' activities in the context of the TPNW obligation. In other words, what does it mean for TPNW parties to engage in remediation measures? And what are the fundamental aims of such measures in the context of Article 6(2) that parties should strive to achieve? Such questions will ultimately reveal the scope of the obligation imposed by Article 6(2), and specifically what the objectives of 'remediation' under the TPNW are, thereby contributing to the overall aims of this article.

Environmental Provisions in Other Nuclear Weapons-Related Instruments
Before proceeding to discuss the meaning of 'remediation', as a first observation, the TPNW is not the first nuclear weapons-related treaty to incorporate obligations addressing environmental damage caused by nuclear weapons-related activities. In fact, certain nuclear weapon-free zone (NWFZ) treaties incorporate provisions designed to protect the environment by prohibiting the dumping of radioactive waste at sea, though admittedly without requiring state parties to address contamination from past radioactive waste disposal or dumping activities. 163 More importantly, however, one existing NWFZ, the Treaty on a Nuclear-Weapon-Free Zone in Central Asia (Treaty of Semipalatinsk) adopted in 2006, explicitly includes the need for state parties to assist in efforts to address environmental damage resulting from nuclear weapon-related activities-though adopting a slightly different formulation. 164 Under Article 6 of the Treaty of Semipalatinsk: [e]ach party undertakes to assist any efforts toward the environmental rehabilitation of territories contaminated as a result of past activities related to the development, production or storage of nuclear weapons or other nuclear explosive devices, in particular uranium tailings storage sites and nuclear test sites.
The inclusion of such an environmental security provisions was of particular significance to state parties in Central Asia given the 456 nuclear weapons test that took place at the Semipalatinsk test site in Kazakhstan by the former Soviet Union between 1949 and 1989. 165 However, this provision is significantly more limited than the obligation imposed by Article 6(2) of the TPNW because it only requires states to assist in environmental rehabilitation in response to an initial request for such assistance by another state party within the region. 166 Despite adopting a similar formulation in the 22 May draft, 167 the final TPNW text, by contrast, obligates affected states parties themselves to undertake and implement measures domestically to remediate contaminated environments 'under its jurisdiction or control', while creating a system of collective responsibility and cooperation towards implementing the TPNW generally, including Article 6(2), by requiring each state party 'in a position to do so' to provide technical, material, or financial assistance to affected parties. 168 For present purposes, however, the most interesting difference between Article 6 of the Treaty of Semipalatinsk and Article 6(2) of the TPNW is the contrasting use of the terms 'rehabilitation' and 'remediation' of areas contaminated by the testing and use of nuclear weapons, respectively in each agreement. Naturally, this point of difference raises the question whether there is any substantial difference in terms of the meaning and objectives of each concept -remediation and rehabilitation-in the present context. 163 See e.g., Treaty on the Nuclear-Weapon-Free Zone in Africa, Art. 7; South Pacific Nuclear-Free Zone Treaty, Art. 7. 164 Treaty on a Nuclear-Weapon-Free Zone in Central Asia (2006) 2970 UNTS. 165 The Soviet Union's Nuclear Testing Programme, Comprehensive Nuclear Test-Ban Treaty Organisation Preparatory Committee, https:// www. ctbto. org/ nucle ar-testi ng/ the-effec ts-of-nucle ar-testi ng/ thesoviet-union snucl ear-testi ng-progr amme/. Accessed 28 Apr 2022. 166 Roscini (2008), pp. 604-605. 167 Section 2.2. 168 See specifically TPNW, Arts. 7(3), 7(4), and 7(6).

Objectives of Rehabilitation and Remediation
It is perhaps useful to start by revealing what remediation does not entail by distinguishing its underlying objectives from 'rehabilitation' activities employed in the Treaty of Semipalatinsk. 169 The term rehabilitation, in ordinary parlance, 170 is often employed in a medical context, and is defined by the Cambridge Dictionary as 'the process of returning to a healthy or good way of life', and more generally as 'the process of returning something to a good condition'. 171 This illustrates the central theme of rehabilitation that seeks to facilitate the recovery, even if not fully, of a damaged object back to a functioning state.
In considering the meaning of the term 'rehabilitation' in the context of environmental damage caused by nuclear weapons testing and use, among other nuclearrelated damage, it is particularly useful to draw from terminology and definitions employed by the International Atomic Energy Agency's (IAEA) 2015 report on 'Policy and Strategies for Environmental Remediation', which provides guidance on the formulation of national policies for remediation of 'radioactively contaminated sites'. 172 Specifically, the report defines 'rehabilitation' as: To restore to good condition, operation or capacity. The term implies that the land will be returned to a form and productivity in conformity with a prior land use plan, including a stable ecological state that does not contribute substantially to environmental deterioration and is consistent with surrounding aesthetic values. 173 In other words, rehabilitation 'emphasises the reparation of ecosystem processes' 174 and the overall improvement of environmental functioning back to a close approximation of its pre-impacted state insofar as possible. For Cooke, who draws upon the meaning of rehabilitation from a medical perspective, environmental (or ecosystem) rehabilitation essentially means 'to repair and replace the essential or primary ecosystem structures and functions which have been altered or eliminated by disturbance'. 175 Accordingly, although the idea of rehabilitation is not oblivious to the often impossibility of returning an impacted environment back to its unimpacted 'natural state', or 'historical trajectory', 176 it nonetheless alludes to a more ambitious objective and end state, with the intention or goal of recovering or restoring the functioning of an environment back to its former state as far as possible. 177 Remediation, however, seems to reflect a more limited concept, and ordinarily revolves around 'the process of improving or correcting a situation', 178 or 'the action of remedying something, [especially] the reversal or stopping of damage to the environment' caused by a particular act or omission. 179 This concept therefore alludes to an initial corrective function by addressing environmental damage and contamination caused by a specific activity or source of harm in order 'to manage the risks to humans being posed by contaminated areas'. 180 Indeed, Telesetsky, Cliquet, and Akhtar-Khavari have described remediation as 'a legal response expected from someone who has caused damaged to a site but the obligation on the individual is simply to return an area back to the condition before the harm was caused to it'. 181 Likewise, the IAEA 2015 report offers a useful definition of 'remediation' in the context of nuclear-related contamination: Any measures that may be carried out to reduce the radiation exposure from existing contamination of land areas through actions applied to the contamination itself (the source) or to the exposure pathways to humans. 182 This understanding of the term 'remediation' was endorsed by Article 36 and the IHRC during the 2017 Conference, who noted that remediation, in the context of nuclear weapons-related contamination, 'can help reduce levels of radiation, prevent radioactive materials from migrating, and minimize the contact that humans have with such contamination'. 183 In essence, remediation reflects the objective of correcting past damage by removing pollutants or contaminants introduced by human activity, in this case the testing and use of nuclear weapons, in order to reduce the impact of such past activities for both humans and the natural environment. 184 Given these above definitions, there are clearly various conceptual differences between the overall scope and objectives of remediation and rehabilitation activities. First, remediation and rehabilitation have different 'targets' against which their respective activities and objectives are pursued. Lima et al., for example, in discussing the conceptual and practical differences between remediation and rehabilitation activities, have observed that remediation efforts generally target 'soil, water, [and] human health' and represent a specific attempt to remove contaminants from these 'targets' in order to reduce sources of human exposure to contaminants. 185 By contrast, the authors suggest that rehabilitation takes a broader approach, focusing on the wider condition of the 'land' or 'site' where the damaged environment is based. 186 In this sense, rehabilitation takes on a managerial dimension, looking at the bigger picture in order to 'optimize local land management capacity' during the recovery of damaged environments, 187 whereas remediation remains a more focused activity that targets a specific form of harm through a process of decontamination as an initial, corrective step.
Second, and relatedly, in contrast to the onerous, more far-reaching aims of rehabilitation measures, environmental remediation often has 'little consideration for reviving previously existing ecological conditions in an area'. 188 Instead, remediation is principally concerned with removing the sources of environmental damage and forms of dangerous exposure, such as radioactive contaminants, due to their detrimental impacts on humans. 189 As the 2015 IAEA report observes: It is important to note that remediation does not involve the complete removal of the contamination and that the more informal term 'cleanup' (i.e. to make a site clean, free from impurities) is not to be taken as being synonymous with remediation. Similarly, the terms 'rehabilitation' and 'restoration' may imply that the conditions that prevailed prior to contamination can be restored... 190 Nevertheless, it is apparent that some commentary discussing the inclusion and development of environmental remediation within Article 6(2) use the terms remediation and rehabilitation either interchangeably or by viewing rehabilitation strategies as forming part of overall remediation efforts. 191 This could suggest that in the TPNW context at least, commentators consider the terms to have a somewhat synonymous meaning, despite generally endorsing the understanding of remediation defined above, as evidenced by the briefing paper published by Article 36 and the IHRC in June 2017. 192 However, it is suggested that such conflation and interchangeable use of each term should be avoided in order to avoid conflation between the specific objectives of remediation and rehabilitation outlined above that make each concept distinguishable in terms of their overarching goals. Evidently, remediation reflects a less ambitious concept based around merely removing sources of contamination, particularly in comparison to the more far-reaching goals of rehabilitation, which seeks to facilitate wider environmental recovery of contaminated areas back to a pre-existing (or at least a close approximation) state of functioning. But although the objectives of rehabilitation are understandingly appealing in advancing loftier ambitions, one must remain aware of the fact that in many circumstances, the 'full' decontamination or rehabilitation of a contaminated environments may not always be feasible or practically possible depending on the nature and type of harms being addressed. Mbengue, for example, in discussing environmental damage and restoration in the context of reparations for breaches of internationally wrongful acts by states under the law of state responsibility, 193 emphasises that: the often irreversible character of environmental damage to which the ICJ refers in the quoted passage makes reparation by restitution impossible. Indeed, the reestablishment of the situation which existed before the destruction of ecosystems or the pollution of seas proves most of the time to be practically unworkable. 194 The impossibility of 'full' rehabilitation is particularly noteworthy in the context of addressing environmental damage caused by the past testing or use of nuclear weapons given the long-lasting, diverse, and often irreversible forms of damage that may arise. 195 In fact, the appreciation that returning a contaminated area to its pre-impacted condition is 'rarely, if ever, possible' 196 is recognised implicitly in the TPNW preamble, which notes that the 'catastrophic consequences of nuclear weapons cannot be adequately addressed ', 197 and by the absence of a deadline by which remediation under Article 6(2) should be achieved, to be discussed further below, which alludes to the long-term, progressive nature of remediation efforts which may have no quantifiably measurable completion point. 198 Accordingly, the use of the term remediation in Article 6(2) as defined above with its accompanying limited objectives that focus on correcting existing environmental harms pays heed to this reality. Indeed, if the term rehabilitation was employed within Article 6(2) in a similar vein to the Treaty of Semipalatinsk, this would have imposed a potentially desirable (in terms of its lofty goals and ambition), but often unobtainable goal that would have set affected TPNW parties up to fail from the very beginning. Instead, by avoiding terminological conflation and maintaining a strict adherence to the more limited, but potentially attainable, corrective purposes of remediation that seeks the removal of contaminants, clarity can be provided in terms of what is expected of affected states parties when implementing Article 6(2) by clearly delineating the contours and objectives of remediation activities generally. 193 See Draft Articles on Responsibility of States for Internationally Wrongful Acts with Commentaries, UN Doc. A/56/10, Yearbook of the International Law Commission, 2001, Vol. II, Part Two, Art. 36(2). 194 Mbengue (2016), pp. 293-294. 195 See Sect. 2.1. 196 Docherty (2021b Of course, this conclusion does not rule out the possibility that certain affected TPNW parties could engage in additional measures designed to restore ecological integrity back to a pre-existing functioning state in contaminated areas following the removal of contaminants and sources of exposure-thus aligning more closely with the objectives of rehabilitation. In this sense, Article 6(2) arguably operates as a minimal baseline obligation, and nothing proscribes the possibility of states employing further measures to address contamination above and beyond their legally accepted commitments. However, the underlying point raised here is that Article 6(2) as presently formulated does not legally require this of affected TPNW parties based upon the above terminological review.

Temporal Application of Article 6(2)
Alongside the meaning of remediation and the geographical scope of areas to which Article 6(2) shall apply, a final, though equally significant, aspect concerning the scope or limits of the environmental remediation provision of the TPNW are the temporal dimensions of the obligation. Specifically, this section identifies particular characteristics of the application of Article 6(2) on a temporal level, principally by examining where the environmental remediation provision of Article 6(2) apply at different points in time, and equally how long Article 6(2) should be applied for in practice as implementation commences.

Looking Backwards as Well as Forward
The first question to ask is what temporal reach does Article 6(2) have? In other words, this issue involves considering and ultimately determining the scope of application of the obligation under Article 6(2) from a temporal perspective, and specifically whether the environmental remediation commitments of the TPNW is capable of covering past environmental harm and contamination caused by prior testing and use of nuclear weapons, as well as any future harms that may arise as a result of future activities.
Although it is generally understood that treaties do not have retroactive effect, 199 the ICJ in the Ambatielos Case confirmed that states can depart from this basic principle freely if a particular treaty clause alludes to its retroactive application. 200 Moreover, it is entirely possible for a treaty's provisions to apply against a preexisting set of facts, acts, or circumstances that continue to be of relevance after entry into force of the particular agreement in question. 201 Simply put, states may, in negotiating a new treaty, seek to address past acts, situations or other existing sets of circumstances within the newly established treaty regime.
To some extent, the TPNW reflects the latter possibility, in that the positive obligations contained in Article 6 are not limited in application only to future sources of contamination, but instead are to be applied to past contamination from the testing and use of nuclear weapons too. Indeed, the language of Article 6(2) refers only to the need for affected states parties to take 'necessary and appropriate measures towards the environmental remediation of areas so contaminated' by activities related to the testing or use of nuclear weapons. This clearly does not impose any explicit temporal restriction on the operation and application of Article 6(2) only to sources of contamination caused by future testing or use, but rather requires remediation of any areas contaminated as a result of the testing of use of nuclear weapons.
This temporal reach of Article 6(2) aligns with the approach taken towards the clearance of unexploded cluster munition remnants in the CCM. 202 Under Article 4 of the CCM, states parties undertake 'to clear and destroy, or ensure the clearance and destruction of, cluster munition remnants located in cluster munition contaminated areas' 203 -thereby alluding to past use of cluster munitions that have left behind unexploded remnants. However, Article 4(1)(b) additionally states: Where, after entry into force of this Convention for that State Party, cluster munitions have become cluster munition remnants located in areas under its jurisdiction or control, such clearance and destruction must be completed as soon as possible but not later than ten years after the end of the active hostilities during which such cluster munitions became cluster munition remnants.
Evidently, this provision recognises the entirely foreseeable possibility that subsequent cluster munition contamination may occur following entry into force for a state party for a number of reasons, and thus requires the any affected states parties engage in clearance of any future cluster munitions remnants that become known or present with its jurisdiction. 204 It is, of course, abundantly clear that Article 6(2) of the TPNW does not adopt language that is equally as explicit as Article 4(1)(b) of the CCM providing unequivocally for application to both past and future contamination sources. But at the same time, and as noted above, the language employed within Article 6 generally does not impose any explicit restrictions on the temporal reach and application of the positive obligations of the TPNW in any expressly defined sense. Furthermore, when one recalls that environmental remediation was presented to participating states during the 2017 Conference as an analogous, though modified form of clearance, 205 it is perhaps unsurprising that a similarly (though implicitly) broad temporal scope of application of the Article 6(2) remediation obligation was adopted by states during the 2017 Conference. Indeed, this broader temporal reach would reinforce the underlying objective and purpose of remedial measures within humanitarian disarmament treaties, including the TPNW, which aim to 'address ongoing harm from past use and testing as well as any future harm that the treaty might fail to pre-empt'. 206 Finally, is worth comparing the temporal application of Article 6(2) with the more explicitly limited language of Article 6 of the Treaty of Semipalatinsk, which refers only to states parties assisting in remediation efforts of contaminated territories 'as a result of past activities' related to nuclear weapons. 207 This formulation interestingly does not seem to apply to future contamination that may arise, and instead only concerns past contamination and nuclear weapons-related harms that have already occurred given its express language. As such, the fact that similar language that expressly limits the temporal reach of environmental remediation in the TPNW was not adopted during the 2017 Conference supports the wider temporal application of Article 6(2) to future sources of contamination.
Accordingly, it can be deduced uncontroversially that the obligation imposed upon states parties to implement environmental remediation under Article 6(2) covers a broad temporal spectrum of past, present, and future sources of contamination, thereby reflecting (if not explicitly) the approach of the CCM. Yet, this broadened temporal reach takes on even greater practical significance in the nuclear weapons context due to the fact that Article 6(2) requires affected states parties to apply 'necessary and appropriate' remediation measures to areas within its jurisdiction or control contaminated as a result of either the testing or use of nuclear weapons. Indeed, while nuclear weapons have only been 'used' during conflict twice by the US in Hiroshima and Nagasaki in August 1945, 208 nuclear weapons testing was a much more common activity, particularly during the Cold War. According to the Arms Control Association, there has been an estimated 2,056 nuclear weapons test since the first 'Trinity' test in New Mexico, US in July 1945, 209 and the last recorded nuclear weapons test was carried out by the DPRK in September 2017. 210 Today nuclear weapons testing is subject to various prohibitions and under international law including, but not limited to, the Partial Test-Ban Treaty 1963, 211 the Comprehensive Test-Ban Treaty (CTBT) 1996 (which is not yet in force), 212 and the TPNW itself. 213 Additionally, certain scholars have asserted that all forms of nuclear weapons explosive testing is prohibited under customary international law. 214 Nevertheless, it is abundantly clear that addressing the environmental damage and destructive legacy of past nuclear weapons testing activities-as opposed to just the use of nuclear weapons-takes on a particularly pressing significance within the TPNW and nuclear weapons context. Accordingly, the broader temporal reach of Article 6(2), coupled with its application to both the testing or use of nuclear weapons, is a welcome formulation that was imperative and entirely logical in order to ensure the provision's application to environmental contamination caused by nuclear weapons testing, an activity that has been more commonplace than the use of nuclear weapons. Indeed, if participants during the 2017 Conference followed the approach set by the CCM in requiring affected states to engage in remediation of past, present, and future contamination stemming only from the use of nuclear weapons in times of conflict, we would be left in the unpalatable position where only two out of the 2,058 215 nuclear weapons detonations known to have occurred would fall under the ambit of the environmental remediation obligation.

The Long-Term Nature of Remediation
Alongside the application of Article 6(2) to both past and future environmental harms from the testing and use of nuclear weapons, the provision also has an additional temporal element; the longevity of the environment remediation efforts to be adopted by affected states parties. This issue stems from a particular point of difference between Article 6(2) and the analogous clearance obligations of unexploded conventional weapons established by the APMBC and CCM; the difference being the absence of a 'remediation deadline' by which the implementation of Article 6(2) of the TPNW should be achieved. Indeed, both Article 5(2) of the APMBC and Article 4(1)(a) of the CCM set 10-year deadlines by which the clearance of mined or contaminated areas should be completed by states parties. Additionally, each treaty envisages the possibility of negotiating extensions if this deadline cannot be achieved through complex procedures within the institutional settings of each instrument. 216 This absence of a pre-determined timeframe by which the environmental remediation efforts of affected states parties should be completed under Article 6(2) has been criticised, 217 but can be justified on two interconnected grounds. The first, again, relates to the nature and objective of clearance and remediation activities. The imposition of a deadline in the APMBC and CCM contexts ultimately symbolise an 214 For discussion of the existence of a customary international law comprehensive nuclear test-ban, see Tabassi (2009);Green (2011), pp. 9-18. For a contrary view, see Asada (2002), pp. 92-94; Le Mon (2006). 215 That is, the two uses of nuclear weapons over Hiroshima and Nagasaki, and the 2,056 known nuclear tests. 216  'end goal', whereby mined or contaminated areas have been 'fully' cleared. Indeed, the clearance obligations under both the APMBC and CCM have been described by Docherty as 'a quantifiable activity that be completed according to measurable, international standards', 218 reflected by the fact that a completion point is ultimately envisioned in each treaty's respective text. This, of course, does not negate the fact that the demining and clearance process presents a daunting challenge for affected states. Nevertheless, its completion is, for all intents and purposes, 'achievable' on the ground because of the tangible nature of conventional remnants.
This position, however, stands in contrast to the nature of environmental remediation under Article 6(2). Although, Article 6(2) draws from prior clearance obligations in terms of its shared purpose in removing sources of danger posed by toxic remnants to humans, 219 it is readily apparent that the amorphous nature and complex variety of damage and contamination stemming from nuclear explosions represents an unprecedented challenge for states on the ground, and presents a whole new range of distinct forms of harms over an often broad, indeterminate area. 220 Put differently, in the context of mine clearance, a clearing state is ultimately acutely aware of how and where to direct its efforts-in essence, to identify, perimeter mark, and ultimately destroy a particular mine/mined areas. In the context of environmental remediation under Article 6(2), by contrast, the breadth of harms and damage that must be addressed are considerably more diverse and often dispersed without visible indication. It is this diversity of harms and types of remnants being responded to-tangible and amorphous-and the different levels of complexity which makes environmental remediation under Article 6(2) a more complicated, less quantifiable exercise in contrast to clearance activities of conventional remnants.
But the fundamental point to be made is that although the clearance of unexploded conventional remnants can have a realistic 'end' or 'completion' point, the amorphous nature of same can often not be said in the context of amorphous environmental harms caused by nuclear weapons testing and use. Indeed, as discussed in relation to the objectives behind the concept of 'remediation' which instead promotes a corrective function to remove sources of contamination rather than requiring rehabilitation of a contaminated environment back to a pre-existing state of functioning, 221 'full' environmental recovery or restoration is often impossible in some situations-a conclusion that certainly runs through in connection with environmental damage caused by the testing and use of nuclear weapons. And as noted, this impossibility of full recovery is implicitly recognised in the TPNW preamble. 222 In fact, Bolton and Minor observe that certain participants during the 2017 Conference argued that the inclusion of environmental remediation positive obligations in the final text could 'imply that contaminated environments could be fully remediated when this is not the case'. 223 Accordingly, the imposition of a deadline under Article 6(2) would, in many cases, effectively be setting TPNW parties up to fail from the get-go given that certain forms of damage from past nuclear weapons testing and use may be irreversible. In this way, the omission of a deadline makes practical sense.
Second, and related to this point, the omission of any specific pre-determined deadline indicates that environmental remediation under Article 6(2) should be considered an ongoing, long-term endeavour. 224 This, in turn, acknowledges the fact that the nature of environmental harm caused by prior nuclear weapon testing or use often has long-lasting effects taking various forms, while 'remaining fully aware of what cannot be addressed' in recognition of the sometimes irreversible nature of environmental damage from nuclear testing and use. 225 Accordingly, the longevity of environmental remediation efforts pursuant to Article 6(2) was framed 'as a goal to work towards rather than complete' 226 -effectively confirmed by the omission of any pre-determined deadline. In other words, environmental remediation pursuant to Article 6(2 should be continually implemented as a long-term progressive, commitment, by affected states parties, with the cooperation of other TPNW parties pursuant to Article 7, addressing new areas of environmental contamination 'related to the testing and use of nuclear weapons' as and when they arise-be that from past or future testing or use of nuclear weapons. Ultimately, therefore, the absence of a remediation deadline does not undermine the objectives behind Article 6(2), and should not act as a justification for a failure to implement Article 6(2) by states parties, or for not providing assistance and cooperation towards this goal pursuant to Article 7 from other TPNW parties. 227 On the contrary, implementing environmental remediation through various 'necessary and appropriate' measures by states parties has the potential to significantly contribute to the restoration of the natural environment, even if not completely so. 228 The implementation of Article 6(2) therefore constitutes a worthwhile agenda to be pursued continuously be states over time, and corresponds with the underlying humanitarian approach to nuclear weapons adopted by the TPNW, which recognises that some remediation and assistance is better than none at all. 229

Conclusion
obligation before and during the 2017 Conference, the discussion has identified, described, and ultimately examined the overall scope and possible limits of Article 6(2) from a number of perspectives, including the geographical and temporal scope and dimensions of the environmental remediation obligation imposed upon affected states parties, along with more precise issues concerning the limits, overarching objectives, and the very nature of the notion of 'remediation' itself.
Ultimately, it is hoped that the enquiry engaged in here acts as a springboard for additional scholarship surrounding environmental remediation in the TPNW, in order to mirror and complement the extensive research developed in connection with victim assistance under Article 6(1). The very fact that such scholarship has so far remain limited is highly unfortunately, particularly given the potential practical contribution that Article 6(2) could have in addresses sources of contamination from past testing and use of nuclear weapons on the ground. With this in mind, it is also hoped that the analysis and arguments reached should prove insightful for states parties to the TPNW by clarifying the overall scope and contours of the environmental remediation obligation itself. Indeed, while many of the conclusions reached may not be revolutionary or uncontroversial, the clarity offered and consideration of the limits of Article 6(2) in depth from various perspectives should provide a useful informative basis as implementation of environmental remediation proceeds.