The idea that the signalling or communicative effects of a self-defensive or other defensive act can have moral or justificatory force is nothing new for just war theorists. Indeed, it has been a long-held belief by many theorists that the ‘future deterrence value’ of a violent act or threat of a violent act, on both the individual and nation-state level can be morally justified under certain circumstances. On an individual level, in the absence of an effective police force, it is arguably morally justified for the isolated Afghan goat-herder, for instance, to respond with disproportionately lethal force at the moment (say, by shooting a thief attempting to steal one of his goats) if that act will foreseeably deter a much greater future harm from foreseeably occurring later on (say, inviting a gang of thieves to rape and pillage his home a week later if he does nothing).
Theorists also recognize the justificatory force that future deterrence value adds at the nation-state level as well. Indeed, the idea that the threat of violence can be good insofar as it serves to deter a much greater future harm from actualizing down the line is presumably why we think nation-states can permissibly build up armies in the first place and why we think nations can sometimes justifiably launch pre-emptive attacks. These individual and collective cases therefore give credence to the moral significance of social signalling effects built into kinetic acts of harming. However, future deterrence in particular seems often to be the very limited sense in which many just war theorists regard the signalling value of violence to morally matter. Indeed, there seems to be other morally important ways; ways beyond just future deterrence, in which the signalling value of a violent act in war can morally matter. As LTC Bob Underwood notes,
Killing in war eliminates threats but also plays a part in influencing the decisions of other persons beyond those we might kill. This suggests that killing in war has a communicative function, and that the message is an important consideration that can feature in the balance of reasons to kill some but not others in war. This is true provided combatants can permissibly kill some as means to communicate to others. I argue that just combatants, those that fight for just aims, can permissibly kill to communicate and that unjust combatants cannot. This is a new reason to revise our intuition that combatants on both sides hold equal rights to kill, the so-called moral equality of combatants (MEC). 
This is an important point here that Underwood brings up. However, I believe that it is even more important when we consider such claims against the backdrop of a counter-insurgency/counterterrorism paradigm; one saturated with the morally salient features of trust-building and winning hearts and minds that Johnson and Simpson both high-light. That being said, we could go even further and say that not only does killing itself have communicative or signalling value that morally matters with respect to in bello proportionality, but that the way, look, and social presentation in which the killing is done has similar or greater communicative or signalling value as well.Footnote 6
For instance, consider the social signalling effects of the 2013 U.S. drone strike against suspected Al Qaeda operatives in Yemen that turned out to be a wedding procession versus the successful ‘boots on the ground’ Special Forces raid to kill Abu Bakr Baghdadi, head of ISIS, in 2019 . Epistemic uncertainties and kinetic trade-offs aside, the first case arguably would have still given terrorist organizations narrative and imagistic fodder even if the target turned out to be actual Al Qaeda operatives whereas the second case would have provided much less narrative and imagistic fodder even if collateral damage was taken.
These considerations arguably change our typical thinking when it comes to the ethics of drone use, particularly within counterinsurgency and counterterrorism contexts, especially when considered in light of (1) the mid and long-term communicative and narrative effects on the local populace, and (2) the potential for narrative and imagery surrounding such eliminative killing acts to be leveraged by terrorist groups for their own propagandistic purposes.Footnote 7
Consider then the following two mission options.
Option 1: I use my drone intelligence capabilities to locate an unjust, fully liable high-value-target (HVT) who is located far from any noncombatants. I then shoot the HVT with my drone.
Option 2: I use my drone intelligence capabilities to locate an unjust, fully liable HVT who is located far from noncombatants. I then deploy my fully willing SEAL team to enter into a space of increased (but still manageable risk) and then shoot the HVT.
Looked at strictly in terms of eliminative harming trade-offs, ‘body count’ conceptualizations of collateral damage and in the absence of consideration for narrative and signalling effects, it seems questionably permissible for a commander to choose Option 2 over Option 1. If one has the means to eliminatively kill a liable target, with no likelihood of (physical) collateral damage, and with overall less risk to soldiers, then what additional moral reason would one have to needlessly risk soldier lives, even if it turned out the soldiers willingly volunteered to take such risk?
However, once we begin taking into account the moral importance of narrative, social signaling, and imagery in the short, mid, and long-term, our moral calculus arguably changes especially for counterinsurgency/counterterrorism contexts. If, in the short-term, a drone-strike serves to successfully take out five fully liable high value terrorist targets with no collateral damage whatsoever, but the narratives, local rumors, and imagery from the event can be more quickly and effectively reappropriated by terrorist actors to convince the local populace that there was in fact major collateral damage to innocents, then it is hard to count the drone strike as prudentially or strategically sound. At best, it seems like a short-term tactical win taking away from mid to long-term operational and strategic success. And insofar as the in bello action diminishes the overall likelihood of success, the act seems questionably moral as well. Were it the case that we knew that part-and-parcel with a kinetic drone strike we would also be providing terrorist actors narrative and imagistic fodder for future propaganda use deleterious to our overall goal of winning hearts and minds, then, all other things being equal, a combination of ethics and prudence might begin to nudge us away from such drone options. We might instead find it morally and strategically preferable to employ soldiers on the ground at a heightened chance of risk for the sake of the positive narrative effects on the populace such an act would yield or at least for the negative narrative effects on the populace such an act would deny to terrorist adversaries.
At first glance, the argument I am making here sounds identical to those philosophers arguing for the in-principle impermissibility of drones based upon the absence of soldier risk.Footnote 8 This however is not the kind of argument I am advancing here. Indeed, I believe that such accounts are incorrect and that these types of arguments for the prima facie impermissibility of drones because they are ‘riskless’ actually get the order of moral justification completely reversed. Indeed, soldiers derive their justification for fighting and killing in the first place from the justness of their nation’s cause, not from bootstrapping ad bellum moral justification ex nihilo from out of physical risk on the battlefield. It can’t be the case that soldier physical risk itself is necessary in order to fight a just war and/or that such risk is the source of moral justification for in bello harming. Otherwise, it would logically follow that whichever political project (ISIS, Nazi Germany, Soviet Russia, etc.) subjected their troops to more physical risk, intentionally or just by accident, would necessarily have the claim to the moral high-ground. Such a position would also entail the radical implication that since the advent of the shield and the bow and arrow, wars have been getting progressively more and more unjust in lock-step with each technological advancement in weaponry and defensive capacities that increased lethality while mitigating soldier risk. That can’t be the case.
That being said, there is still something important that soldier-risk proponents are getting at and I believe it is the following. Physical risk qua physical risk doesn’t itself provide any additional moral justification for harming and war. However, the communicative and social signalling effects constitutive of demonstrations of physical risk in battle do in fact have moral weight. This is a subtle but important distinction since it is the set of positive downstream goods generated by the signalling act of risk and not the act of risk itself which is the source of moral justification force certain kinds of harming acts. The weight of such signalling acts is particularly morally significant if we consider the potentially beneficial or deleterious second and third order effects such signalling acts will have on our project of ‘winning hearts and minds’ and, conversely, on terrorist groups’ project of doing the same. If we begin scooping those downstream second and third order social effects into our in bello proportionality calculus, then the case for preferring Option 2 over Option 1 begins to find greater moral and prudential appeal. However, it is admittedly tough if not impossible to count these social downstream effects as part of our in bello proportionality calculus beyond a certain predictive window. In particular, given that these second and third order social effects are really hard to predict with certainty, to quantify, and to demonstrate causally, it is arguably much more difficult to count these complicating factors in our proportionality calculations than it is for us to factor brute kinetic effects and trade-offs.
That being said, it is not as if predicting collective human social behavior is completely and totally opaque to us at all times. Accidentally drone striking a mosque or wedding amidst a smart-phone laden public, for instance, will generate certain predictable downstream social effects that are harmful and disruptive to a populace and a mission in a way that goes well beyond the immediate blast radius of the chosen munition. Running a clandestine operation under the cover of darkness will yield another. And while it is arguably incorrect for us to predict every future downstream social harm arising from a singular battle-field act, it is likewise equally incorrect for practitioners and ethicists to treat each kinetic action as somehow occurring in a social vacuum with no regard for downstream social and narrative effects whatsoever. My point here is simply that narrative effects need to be weighed more heavily both ethically and strategically given the twenty-first century informational space in which we now find ourselves.