1 From the Postwar to the Cold War

1.1 Civil War in China

1.1.1 Causes of the Chinese Civil War

Although the Republic of China (ROC) won the Second Sino-Japanese War, the national economy was exhausted, and the war was derided as a “Pyrrhic victory” (Pepper 1978, Chaps. 1–2). The defeated Japanese puppet government and the ROC government and Communist Party of China (CPC), both led by the Kuomintang (KMT, or Chinese Nationalist Party), confronted each other with their own spheres of governance, people, and armies. The victors, the ROC and the CPC, began a struggle for supremacy over China after Japan’s withdrawal. This led to the Chinese Civil War fought between the ROC, led by the KMT, and the CPC. However, as one side had the backing of the U.S. and the other the backing of the Soviet Union, it can be said that it was an international civil war that anticipated the Cold War.

After Japan’s defeat in the war, with the mediation of the United States, which did not want a civil war, the two parties signed the Double Tenth Agreement on October 10, 1945, which set the basic policy of postwar China. The two parties agreed on the peaceful founding of the nation,” “peaceful and democratic reunification of China,” and the “avoidance of civil war. However, problematic issues such as the area of the liberated zone governed by the CPC and the handling of CPC-affiliated troops were postponed, and the country continued to remain divided.

In June 1946, the ROC Army invaded the New Fourth Army area in Huazhong in large numbers, and the Nationalist-Communist Civil War began in earnest (the New Fourth Army Incident). Initially, the ROC Army, which boasted superiority in terms of numbers, continued to have the upper hand. On the other hand, the CPC reorganized its forces into the Chinese People’s Liberation Army (PLA) in February 1947 and attempted to resist, but was repeatedly defeated. Stalin had chosen the initially superior Chiang Kai-shek as his partner. The Soviet Union provided military support to the CPC but did not predict or expect eventual victory.

On the other hand, the KMT and its allies proceeded unilaterally with the constitutional process, holding a National Assembly in November 1946 and enacting the Constitution of the Republic of China (Matsuda 2006 Chap. 1). While the ROC continued its civil war with the CPC, it shifted to a constitutional government in 1947, forcing the election of representatives to the National Convention and legislators under the new constitution. Chiang Kai-shek was elected president at the National Assembly, but the CPC and its allies were completely excluded from the transition process of the constitutional government. Chiang Kai-shek tried to strengthen the legitimacy of the country as a democratic nation and win support at home and abroad, but the forceful election resulted in a split within the KMT, and the democratization of the country, in which the leading political forces for democracy were eliminated by force, did not strengthen support at home and abroad.

1.2 From the “Three Major Campaigns” to the Conquest of the Entire Country

Initially, the ROC Army had the upper hand, but after June 1947, the situation gradually reversed, and decisive progress was made in three military campaigns in late 1948 (Pepper 1978, Chap. 9). In the PLA, these are known as the “Three Major Campaigns.” The first was the Liaoshen Campaign (September 11 to November 2, 1948), a major decisive battle in the northeastern region centering on Shenyang, Liaoning Province. The ROC Army, which had maneuvered over a long distance, was met in battle by the PLA, which had had ample preparation. In the end, the PLA annihilated 470,000 ROC Army troops and succeeded in capturing the northeastern region, and the wheels of the ROC Army began to turn. This was followed by the Huaihai Campaign (November 6, 1948 to January 10, 1949: known in Taiwan as the Battle of Hsupeng). The Huaihai Campaign was a decisive battle in the Zhongyuan (Central Plain) area, where the major transportation routes from east to west and north to south intersected. On this occasion, the PLA’s Zhongyuan Field Army and East China Field Army defeated 550,000 ROC Army troops. Finally, there was the Pingjin Campaign (November 29, 1948 to January 31, 1949). This was an offensive and defensive battle between Beiping (another name for Beijing) and Tianjin. Here, the PLA launched an all-out attack against Beiping and Tianjin, which were defended by an ROC Army numbering 520,000 that had withdrawn from the Liaoshen Campaign.

In Beiping, the ROC Army negotiated with the PLA for a “bloodless” victory. (Pepper 1978, Chap. 9) The CPC raised the issue of peace negotiations and put pressure on Chiang Kai-shek, the advocate of war. As a result, Chiang Kai-shek stepped down from his duties as president in January 1949, and the advocates of peace proceeded with peace negotiations with the CPC. However, the “peace agreement” proposed by the CPC contained a list of unilateral demands that amounted to a “demand for total surrender,” which led the peace faction of the KMT to reject peace with the CPC.

With the peace negotiations in limbo, on April 21, 1949, Mao Zedong and PLA commander-in-chief Zhu De issued the order for all troops to advance, and they crossed the Yangtze River. The war was no longer over, and on April 24, they succeeded in capturing the capital city of Nanking (Nanjing). On October 1, the People’s Republic of China (PRC) was established.

The PLA steadily continued to occupy and exert its control over Mainland China. However, the PRC maintained the status quo in Hong Kong and Macau in order to avoid a decisive confrontation with the United Kingdom, which believed that it was possible to embrace the PRC, and in response, the United Kingdom recognized the PRC the following January 1950. In May 1951, the PLA moved into Lhasa, Tibet, and in the first half of 1950, the CPC’s power in Mainland China was established.

1.3 Causes of CPC Victory and the Impact of the Chinese Civil War

At the outbreak of the civil war, there was a more than threefold difference between both sides in terms of military power alone, but the CPC won the war. The PRC’s publications tend to emphasize the moral righteousness of the CPC, which represented “democracy and peace,” and the disaffection caused by the reaction, arrogance, and corruption of the KMT, aided by “U.S. imperialism,” as well as the terrorist attacks on leftist intellectuals. On the other hand, KMT publications tend to emphasize international factors, such as “inadequate” U.S. support for the ROC and the Soviet Union’s covert military support for the CPC.

Inflation, unemployment, and corruption during the postwar turmoil, along with internal disunity, caused the ROC to lose its credibility and fail to mobilize the civil war-averse public and the international community into a war against the CPC, despite its victories against external enemies. The CPC, on the other hand, took advantage of this social unrest and, through “land reforms,” succeeded in mobilizing the peasantry and others militarily (Pepper 1978).

In addition, factors that contributed to the CPC’s victory include the fact that the CPC had more military support in the Soviet-occupied northeast (the former Manchuria) than the ROC had expected; that the CPC was able to use northern Korea, which had been occupied by the Soviet Union, as a strategic hinterland; and that the U.S.’s military support for the ROC, which wanted to continue peace negotiations, was insufficient.

After the formation of the PRC, the ROC under the leadership of Chiang Kai-shek moved to Taiwan in December 1949 and developed a plan to counterattack the mainland. The PRC, on the other hand, stood for the “liberation of Taiwan” and the two sides continued to confront each other militarily. However, with the Korean War, the division and confrontation of the Chinese nation across the Taiwan Strait became fixed.

In Taiwan, the KMT became a one-party dictatorship in which an alien minority ruled over a large number of mainland Chinese who had been subjected to Japanese colonial rule. Also, the establishment of the Communist regime in Mainland China also enabled the Democratic People’s Republic of Korea (DPRK) to attempt to reunify the country by invading the south with logistical support, which led to the Korean War.

2 The Allied Occupation of Japan and the 1951 Peace Settlement

2.1 The U.S. Occupation of Japan

Japan’s surrender to the Allied Powers in early August 1945 in the form of acceptance of the Potsdam Declaration enabled the U.S. government to exclusively exert its influence on the Occupation of Japan for more than six years. Formally, the authority of the General Headquarters, the Supreme Commander for the Allied Powers (GHQ/SCAP), was under the Far Eastern Commission (FEC) in Washington, the decision-making body organized by 11 Allied countries including Permanent Members of the U.N. Security Council for the occupation policy, while the Allied Council for Japan (ACJ), an advisory body to the SCAP composed of the U.S., the British Commonwealth, the Soviet Union, and China, was established in Tokyo. However, the U.S. government was often able to carry out its policy intentions by invoking its veto power or emergency interim directive power in the FEC.

The presence of Douglas MacArthur, nominated as the SCAP, further strengthened the character of the U.S. occupation. Driven by a strong sense of duty, with the belief that transforming militaristic Japan into a democratic and peaceful nation was a noble God-given mission, together with his incredible political sense, MacArthur shortly succeeded in establishing authority over the Japanese people and government based on his cooperative relationship with the Emperor Showa. Under his absolute power, Japan was largely isolated from the international situation as well as U.S. domestic politics and concentrated on demilitarization and democratic reforms (Schaller 1985; Cohen and Iriye 1990; Fukunaga 2021).

2.2 Demilitarization and Democratization Reforms

The U.S. government believed that Japan’s ability to wage war must be destroyed so that it would never again attempt to challenge the international order, and that the political, economic, and social systems that had become breeding grounds for militarism must be transformed into free and democratic systems. The enforcement of demilitarization, including the arrest of war criminals, the dismantling of the Imperial Japanese Army and Navy, and the purge of the people that was identified to be responsible for the Asia Pacific War, was launched at the beginning of the occupation, followed by democratic reforms.

The formulation of the 1947 Constitution was the highlight of the series of occupation reforms. The reluctance of the Japanese government to revise the Meiji Constitution made the Government Section of GHQ determine to draft the new Constitution that would provide more freedom and equality to the people. The process by which the Japanese government was virtually forced to accept the U.S.-made Constitution damaged its legitimacy in postwar Japan. On the other hand, the emperor as a “symbol” without political power, the parliamentary cabinet system, and basic human rights was institutionally guaranteed, which in the long run facilitated liberal democracy as norm in the Japanese society. Reforms in the political sphere, such as the amendment of the Election Law to allow women’s suffrage or the enactment of the Diet Law that stipulated the supremacy of the Diet over administrative organs, and the social and economic reforms represented by the expansion of labor rights or land reform, along with the dismantling of zaibatsu and anti-trust policies, supported this norm on the outer fringes of the Constitution. And Article 9, stipulating the renunciation of war, became the foundation of postwar Japanese foreign policy (Dower 1999; Iokibe 2007; Miller 2019).

Major demilitarization and democratization reforms were completed within about two years, and after around 1947–1948, the U.S. began to focus on stabilizing and rebuilding the Japanese economy. The shift in occupation policy coincided with the growing tensions between the East and the West both in Europe and Asia, and thus took an ideological hue. While the economic revival was a necessary step that had been envisioned by the U.S. government when it formulated its occupation policy for Japan during the war, the program of rebuilding the Japanese economy was accompanied by the consolidation of state power lest Japan should fall into communist hands, which was based on the U.S. government’s policy toward Japan (NSC 13/2), a very product of George F. Kennan’s containment policy. This is why it is called the “reverse course.” (Schaller 1985; Gaddis 2005; Kennan 2020).

The U.S. government undertook economic stabilization program for Japan in the end of 1948, and Joseph M. Dodge, president of the Bank of Detroit, dispatched to Tokyo, provided the Yoshida Shigeru cabinet guidance on a financial and monetary contraction policy, including the fixing the exchange rate to 360 yen to one U.S. dollar. The Dodge Line, a series of drastic policies for Japan designed to promote its economic independence trying to eliminate subsidies, government loans, and multiple exchange rates, rapidly brought the inflation that had plagued occupied Japan to a halt. In the long run, this had the effect of promoting management rationalization and fostering international competitiveness, along with the easing of the reparations policy, the GARIOA and EROA program, the limited resumption of private trade, as well as the moderating the antitrust policies also implemented between 1947 and 1949. It is important to note that the Yoshida cabinet decisively carried out this drastic policy, although the Dodge Line created a severe depression and social unrest in Japan in the short term. Yoshida’s Liberal Party, with its roots in prewar political parties, adapted to the demilitarization and democratic reforms and won the general election in January 1949 with a comfortable majority after the collapse of center-left coalition governments with all-out support from the Government Section. From the U.S. perspective, the goal of nurturing Japan as a member of the West could be supported by indigenous anti-communist groups. The cooperative relationship between the U.S. government and conservative forces thus created would become the driving force behind Japan’s long-term conservative rule (Gordon 1993; Kusunoki 2013; Miller 2019).

2.3 The Choice of Majority Peace

Another theme of the second half of the occupation was the peace treaty with Japan. In order to clarify Japan’s national responsibility for the Asia Pacific War, it was necessary for the Allied powers to create a punitive peace treaty to Japan. On the other hand, the peace treaty also had to prevent the next war: many U.S. and British leaders shared the view that the Treaty of Versailles after World War I was too harsh on the defeated Germany, which foreshadowed the emergence of Adolf Hitler and Nazi Germany, consequently leading to World War II. The “lessons of the past” for the Allies were serious for Japan as well, since the enforcement of peace by the victors on the losers could plunge the latter into national bankruptcy, obviously shown in Germany. That is why the Ministry of Foreign Affairs began preparatory studies for a peace treaty at the start of the occupation.

The balance between the conflicting demands of punitiveness and non-punitiveness was tilted heavily in favor of the latter by the Cold War. Peace drifted away as the environment for an agreeable peace with Japan between the U.S. and the Soviet Union was largely lost, and the demands that would have been included in a peace treaty in the past were accomplished through a prolonged occupation. More than that, the U.S. Cold War strategy determined the nature of the peace treaty—rather than seeking to hold Japan accountable for the war, the U.S. government placed more importance to welcoming Japan into the Western camp through the peace treaty with Japan and building the security framework for non-Communist countries in the Asia Pacific region. The Harry S. Truman administration negotiated with the Allies on a policy of “soft peace” that would not impose political, economic, or military restrictions on Japan and would waive reparations. Meanwhile, the establishment of the People’s Republic of China in October 1949 and the breakout of the Korean War in June 1950 increased Japan’s strategic value, necessitated U.S. long-term strategic control of Okinawa and the Ogasawaras, the stationing of U.S. forces on the Japanese mainland for the defense of Japan as well as the entire Asia Pacific region, and the rearmament of Japan itself as conditions for peace for the U.S. military (Schaller 1985; Kusunoki 2013).

Prime Minister Yoshida Shigeru decided to stake Japan’s future on the U.S.-led peace process. In Japan, left-wing political parties and intellectuals advocated the “Three Principles of Peace”— peace with all Allied countries, neutralization of postwar Japan, and opposition to military bases for any foreign forces—which later became “Four Principles of Peace,” adding one more principle, the opposition to Japan’s rearmament. Yet the overall peace was not feasible as long as the Cold War continued, although it was undeniably ideal, and virtually meant the duration of the occupation which had been already prolonged for more than four years and begun eroding the spirit of independence within the Japanese people. Therefore, he believed that Japan should restore its independence as soon as possible through concluding the peace treaty with countries of the willing, or the Western countries. As one of the prominent anglophiles, Yoshida considered that Japan would be able to regain its international status and pursue its survival in cooperation with the United States and other liberal countries.

It was inevitable that Yoshida decided Japan’s dependence on the United States for its security after the occupation. Considering that the Cold War nearly plunged the United Nations into dysfunction, and Japan’s geographical environment did not allow it to choose neutrality, Yoshida reached the conclusion that Japan, with the Peace Constitution, had no choice but to look to the U.S. for defense guarantees, which could be ensured by offering military bases in the Japanese mainland to U.S. forces. This was the very decision from the realistic viewpoint of international relations, but interestingly, Yoshida was negative to rebuild Japan’s own forces for self-defense before the peace process ended. While he thought that Japan needed rearmament as a sovereign nation in the future, he feared that it would place a significant burden on the fragile Japanese economy at that moment. Seeing communism as a political rather than a military threat, it was more realistic fear for him that economic instability would trigger social unrest, which would be exploited by Communists and consequently hand Japan over to Communist camps from within.

A security agreement between Japan and the U.S. with the provision of bases at its core and the future rearmament of Japan were agreed upon, through negotiations between both governments from the end of January to February 1951. Although Japan and the U.S. were severely divided over the issue of rearmament, the U.S. side decided to proceed with the peace negotiations after confirming the Yoshida administration’s intention to build a self-defense capability (Kusunoki 2009; Pyle 2018; Miller 2019).

2.4 Peace Treaty with Japan and Japan-U.S. Security Treaty

It was not necessarily an easy task for the Japanese government to accept the Peace Treaty with Japan, signed in San Francisco on September 8, 1951. Besides overseas properties held in the Allied countries to be generally seized, Japan was required to provide its assets held in neutral countries to the International Red Cross for the purpose of appropriating them to compensate captive Allied servicemen. As for territory, Japan was supposed to renounce all right, title, and claim to all overseas territories as well as the Kuril Islands and the southern part of Sakhalin, and Okinawa and the Ogasawara Islands were not returned to the mainland at this stage, although they were designed to be interpreted as potentially sovereign to Japan. Furthermore, the arrangements for territorial treatments were rather ambiguous—the scope of rights, title, and claims to be renounced by Japan was not always clear, and the destination of these claims was not specified, which constituted one of the origins of the territorial disputes between Japan and its neighbors.

At a time when the memory of the war was still fresh in the minds of the Allies, it was probably impossible to completely erase the “punitive” nature of the peace treaty. The very fact that power was still a decisive factor in international politics made it inevitable for countries concerned to accept the borders drawn by the powers at the end of the war. Nevertheless, in principle the San Francisco Peace Treaty imposed no political, economic, or military restrictions on Japan, and restrained demands on the Japanese government regarding claims and reparations, without mentioning Japan’s responsibility for the Asia–Pacific War. The idea of creating a legitimate order even for the losers was injected into the system of power politics, however imperfect it was, the Peace Treaty with Japan can be regarded as a “fair and generous treaty” (Eldridge 2001; Hara 2015; Kawashima and Hosoya 2022).

The Japan-U.S. Security Treaty, concluded on the same day as the Peace Treaty with Japan, was an unequal arrangement for Japan in that obligations and rights between both countries were conspicuously asymmetrical. Above all, Japan was obliged to provide bases in the Japanese mainland to the U.S., while the U.S. forces stationed in Japan were not necessarily required to defend Japan. Regardless of the text of the treaty, the presence of a certain size of U.S. military power in Japan was expected to function as deterrence against the Soviet Union, but the fact that formally no mutual defense relationships existed between both countries was understood as a flaw in the treaty in Japanese political and diplomatic circles, along with the arrangements that the U.S. forces stationed in Japan could be used to suppress civil unrest and disturbances, and the term of the treaty was not set. Furthermore, the possibility that the U.S. military bases in Japan would be used for international peace and stability in the Far East, the most important role from the U.S. point of view, gave rise to fears of entrapment among Japanese. The gap between the perceptions and sensitivities of Japan and the U.S. over text of the treaty as well as the role of the U.S. forces in Japan became an intrinsic destabilizing factor in the Security Treaty, casting a shadow over U.S.-Japan relations in the 1950s (Packard 1966; Kusunoki 2009).

The Soviet Union and other eastern countries participated in the peace conference but did not sign the treaty. China, whose legitimacy was disputed by the Communist and Kuomintang governments, was not invited, and the Japanese government opted to make peace with the Kuomintang government, finalized as the Treaty of Peace between Japan and the Republic of China in April 1952. This was because it was deemed difficult to establish diplomatic relations with the Communist China that had signed a Treaty of Friendship and Mutual Assistance with the Soviet Union and was at war with UN forces supporting North Korea, but it is also undeniable that the U.S. government strongly desired Japan’s peace with the KMT regime. India and Burma did not come to the peace conference. Diplomatic relations with Southeast Asian countries necessitated at first negotiations over reparations, which they were exceptionally recognized the right to claim in the form of the services of the Japanese people in production. As a result of the priority given to welcoming Japan into the Western camp, it can be said that the Peace Treaty with Japan did not necessarily have an immediate effect on building relations between Japan and its neighboring countries.

Nevertheless, the peace treaty enabled Japan to be linked to the international monetary and free trade system and to enjoy the security and economic assistance provided by the U.S, which had the effect of promoting Japan’s economic recovery and supporting political and social stability in the long run. At the same time, the Peace Treaty served as a framework for building relations among the nations constituting and involved in the Asia–Pacific region, ensured by several security agreements that the United States concluded with non-Communist countries in the region, including Japan. The Peace treaty and mutual defense arrangements consequently functioned as a “system” that maintained the regional order and complemented the collective security system of the United Nations and the free trade system. One obstacle to the sustainability of the “system” was Japan’s domestic desire for “independence” from the U.S., or for neutrality from the East–West conflicts, especially among leftist forces. The other was the issues that were not necessarily addressed in the peace treaty: when concepts that were excluded from the design of the peace treaty, such as compensation for individuals and apology and remorse for Japan’s colonial rule, are introduced into interstate relations, the framework of the “system” is no longer able to handle them. By the 1990s, when human rights norms became mainstream and nationalism in Northeast Asian countries grew stronger against the backdrop of economic development, the function of the peace treaty as a “system” may have reached its limits.

3 The Korean War

3.1 Divided Occupation by the U.S. And the Soviet Union and the Establishment of the North–South Divided Regimes

In August 1945, the Korean Peninsula was liberated from 35 years of Japanese colonial rule. However, it was not an immediate independence. This is because the United States and the Soviet Union had already agreed to divide and occupy the peninsula along the 38th parallel. Since the U.S. and the Soviet Union were already engaged in a struggle for hegemony over the postwar world order, there was a high possibility that the divided occupation would result in the establishment of a divided state. However, even within Korea, there were divisions carved into society in the process of modernization under Japanese colonial rule. Specifically, there were splits caused by people’s relative cooperation or clear resistance to the Japanese rule, as well as class divisions between landowners and peasants, as well as capitalists and laborers. At the same time, it should also be noted that these social divisions were politicized as the left–right conflict over the anti-Japanese national independence movement. These splits in the domestic political and social spheres and the U.S.-Soviet divided occupation, which intensified the inter-Korea conflict, aggravated each other, and in 1948, the Republic of Korea (ROK), an anti-communist South Korea, was established south of the 38th parallel under U.S. military rule, and the Democratic People’s Republic of Korea (DPRK), a communist North Korea, was established north of it under Soviet occupation. These two nations existing in parallel formed a divided system in which each asserted its own exclusive legitimacy.Footnote 1

3.2 Outbreak, Development, and Consequences of the Korean War

Despite the establishment of the North–South divided regimes, both the North and the South shared the position that they had the legitimacy to govern the entire Korean Peninsula and that the other side was merely a puppet of a major power. Therefore, neither side was content to maintain the status quo, and both sought opportunities for reunification, even if it meant mobilizing their military forces. However, the U.S. and the Soviet Union, which were cautious about becoming embroiled in a war, sought to restrain both sides. But with the victory of the Chinese Communist Party in the 1949 Chinese Civil War and the establishment of the People’s Republic of China (PRC), Josef Stalin of the Soviet Union allowed Kim Il Sung, the North Korean leader to invade the South on the condition that they would gain the support of China. Stalin aimed to expand international communism across the entire Korean Peninsula and even to Japan, while Kim Il Sung aimed to achieve the reunification of the Korean Peninsula.

China was cautious, wanting to prioritize the opportunity to invade Taiwan to achieve one China, but in the end, Mao Zedong decided to give substantial support to North Korea’s invasion of the South by sending back Korean troops who had participated in the Chinese Civil War. This was because Mao Zedong regarded the Korean War as an extension of the Chinese Civil War (Shen and Xia 2020). As a result, the Korean War began on June 25, 1950, with the aim of North Korea’s invasion of the South and military reunification.Footnote 2 However, North Korea claimed that it was only responding to aggression directed upon itself, a position it still maintains to this day.Footnote 3

South Korea was founded with rightist Rhee Syngman as its first president. While leftist forces were originally dominant in the country, the U.S. military government suppressed them, and a rightist government was established. South Korea was inferior to North Korea in terms of political stability and military and economic power. Therefore, immediately after the outbreak of the war, North Korea’s invasion of the South was successful, and the reunification was imminent. As such, in order to defend South Korea, the U.S. convened the U.N. Security Council in the absence of the Soviet Union, which was one of the permanent members having veto, and formed the United Nations Forces with the other 15 like-minded nations, including the U.K, France, and so on., to participate in the war. As the Cold War between the U.S. and the Soviet Union intensified, the U.S. sought to change its policy in the wake of the Korean War, from the traditional defensive “containment” against the Soviet Union to a “roll back” to counter the expansion of communism by military means and to retake the areas that had been under the Soviet influence. In addition to pushing the North Korean army back to the north, it also invaded the north across the 38th parallel and closed in on the China-North Korean border (Cumings 1990).

Faced with a threat to its own security, China brought the Chinese People’s Voluntary Army into the war and pushed the UN forces back to the south. As a result, after more than two years of back-and-forth fighting across the 38th parallel, the UN forces, the Korean People’s Army (North Korean Army), and the Chinese People’s Voluntary Army signed the Korean War Armistice Agreement on July 27, 1953, and the Military Demarcation Line, which roughly coincided with the 38th parallel, was established, marking a “ceasefire” in the Korean War (Foot 1990). Syngman Rhee was dissatisfied with the failure to achieve the reunification and chose not to sign the agreement, although he did not want to hinder its effectiveness. Later, however, the South Korean government changed its position that the South Korean army was a party to the agreement because it had acted in unison with the UN forces. Thus, while this “ceasefire” served to halt the Korean War, no peace treaty or peace agreement has yet been signed to legally end the war. Both South Korea and North Korea went on to firmly establish different political and economic systems, and based on these systems, pitted the rivalling systems of South and North against each other. With South Korea’s sustained development, political democratization, and the end of the global Cold War, the regime competition ended in favor of South Korea. However, as North Korea has chosen to avoid South Korean-led reunification and prioritize the survival of its own regime, the North–South division will continue.

3.3 Legacy of the Korean War

The Korean War broke out when Kim Il Sung of North Korea, with the support of China and the Soviet Union, attempted to overcome division and achieve the reunification by military means. The U.S. along with other U.N. forces and China’s People’s Volunteer Army joined the war, turning it into an international war. The Soviet Union also got involved in a limited way by deploying air force pilots. In addition, Douglas MacArthur, the United Nations Forces Commander, advised the U.S. President Harry Truman to drop atomic bombs not only on North Korea but also on major cities in northern parts of China and the Far East Soviet Union. If this had been done, it would have inevitably led to the Third World War. In the end, however, this option was not chosen, and the battlefield was limited to the Korean Peninsula (Wada 2014).

For the Korean Peninsula, the entire land became a battlefield and was left in ruins. In addition, the war caused a great loss of human lives, including 1.3 million South Koreans and 2.5 million North Koreans including not only the military but also civilians, or more than 10 percent of the total population of the Korean Peninsula. What is more, because it was a civil war in which Koreans massacred Koreans and because many areas had been occupied and controlled by both North and South Korea, civilians were also killed in those areas (Cumings 2010). These experiences resulted in the subsequent strengthening of the dictatorial political systems of North and South Korea. In South Korea, the existence of all leftist forces was outlawed, and in North Korea, Kim Il Sung purged and exiled his political rivals and opponents. This further strengthened the dictatorships of Syngman Rhee and Kim Il Sung.

In 1953, the Mutual Defense Treaty between the United States of America and the Republic of Korea was signed, and the U.S. and South Korea became allies, with U.S. forces continuing to be stationed in South Korea in case of an emergency on the Korean Peninsula. The Chinese troops stationed in North Korea were withdrawn in 1958, but North Korea concluded a Treaty of Friendship, Co-operation and Mutual Assistance with both the USSR and China in 1961. In this way, the Cold War system on the Korean Peninsula was further solidified with the establishment of a system in which Japan and the United States supported South Korea, and China and the Soviet Union supported North Korea.

3.4 The Korean War and Japan/East Asia

When the Korean War broke out, Japan was under the U.S. occupation and had no choice but to become involved in the Korean War under the leadership of the GHQ (General Headquarters of the Supreme Commander of the United Nations), the main body responsible for the occupation of Japan. Above all, Japan became a sortie base as the U.S. forces in Japan entered the war. It also served as a logistics base for the production and supply of goods necessary for the war effort, given that the war dragged on for more than three years. In this way, Japan, which was supposed to be a “peaceful nation” according to the terms of demilitarization under the Constitution of Japan that had been enforced in 1947, was transformed into a “base state” with the Korean War (Nam 2016). In addition, it has become clear in recent years that UN forces mobilized hundreds of Japanese working at U.S. military bases for the war effort, resulting in at least 58 war dead (Fujiwara 2020, p. 318). What is more, the “special procurement for Korea” that accompanied the war contributed greatly to Japan’s postwar economic recovery.

And the war led to the “rearmament” of Japan with the Police Reserve Force, the National Safety Forces, and the Japan Self-Defense Forces, as well as the conclusion of the Security Treaty between Japan and the United States of America, which led to Japan’s deep integration into the anti-communist block led by the United States. Because of Japan’s historical experience of invading and ruling Korea, Japan and South Korea did not enter into a formal alliance, but a relationship was established in which Japan would help ensure to South Korea’s economic development and political stability through economic cooperation, and to South Korea’s superiority in the regime competition between North and South Korea.

Furthermore, the Korean War had a profound impact on East Asian international relations with China, and thereafter became the direct origin of the Cold War between the United States and China in the 1950s and 1960s. Immediately after the outbreak of the Korean War, the U.S. dispatched the U.S. Seventh Fleet to the Taiwan Strait and imposed a blockade of the strait to suppress any chance of a Chinese invasion of Taiwan. Thereafter, the U.S. and Chinese armies exchanged fire as the main forces of both sides in the Korean War. And even after the armistice, the Korean Peninsula became part of the Cold War between the U.S. and China, with the U.S. and China serving as the backers of the militarily opposed South and North Korea, respectively.

4 Taiwan Strait Crisis: An “Extension” of the Chinese Civil War

4.1 The 1954–55 Crisis: The First Taiwan Strait Crisis

After 1949, the civil war in China continued across the Taiwan Strait, with the People’s Republic of China (PRC) calling for the unification of China through the “liberation of Taiwan,” and the Republic of China (ROC) on Taiwan calling for the unification of China through counterattacks on the mainland (Lin 2016, Chap. 8). The reality of the “Cold War in Asia” was that, even though it was a Cold War system on a global basis, locally, the goals were “national unification” and the “accomplishment of revolution,” and many actors were waging a heated battle for victory. With the Korean War, the United States declared the neutralization of the Taiwan Strait and had its Seventh Fleet patrol it constantly.

The PRC became a nationwide regime, but it exterminated 2.4 million people between 1950 and 1953 through a campaign to eliminate the remaining forces, including the ROC’s regular army and guerrilla forces. The PRC neutralized the former Kuomintang (KMT, or Chinese Nationalist Party) forces through the establishment of a national surveillance system, as well as ceaseless political struggles, such as the Campaign to Suppress Counterrevolutionaries and the Three-anti and Five-anti Campaigns.

In Taiwan, the KMT rebuilt its one-party dictatorship, and its efforts to eliminate the Communist Party of China’s (CPC) infiltration efforts went too far, leading to a major purge known as the White Terror (Matsuda 2006, Chap. 4). Thus, a pair of divided states meant the birth of a pair of police states. The ROC launched a series of small-scale counterattacks on the mainland, including maritime assault operations, but these were completely thwarted by the PRC.

The military confrontation across the Taiwan Strait continued, and the ROC attempted to use the Korean War to launch a counterattack on the mainland from the north, which was halted by the U.S. After the Korean War ceasefire in 1953, the PRC launched an offensive against the remote island areas off the coast of Zhejiang Province, which were then under ROC control. It took about a year from 1954 to successfully occupy this area. During this period, the United States even considered using nuclear weapons against the PRC, but both the United States and China continued to avoid direct conflict.

The PRC succeeded in driving out the ROC Army from the Zhejiang coast, but it also resulted in the Formosa Resolution and the Mutual Defense Treaty between the United States of America and the Republic of China (Sino‑American Mutual Defense Treaty), which encouraged closer security relations between the U.S. and ROC on Taiwan. The U.S. sent a navy escort to oversee the withdrawal from the above-mentioned islands (Garver 1999, this chapter).

In July 1955, Premier Zhou Enlai called for the “peaceful liberation” of Taiwan and for talks with the “responsible authorities in Taiwan’s provinces.” At the same time, Mao Zedong advocated the Hundred Flowers Campaign and allowed the democratic factions allied in the struggle against the Kuomintang to criticize the Communist Party. In June 1956, however, Mao launched the Anti-Rightist Campaign, an all-out crackdown on dissenters. This may have been due to his fear that incidents in Eastern European countries such Poland and Hungary against the socialist regime would also occur in the PRC, but on the other hand it also meant that compromise with the CPC would be dangerous for the KMT.

4.2 The 1958 Crisis: The Second Taiwan Strait Crisis

The Sino‑American Mutual Defense Treaty limited the territory of the ROC to be defended by the United States to Taiwan and the Penghu Islands and excluded the outlying islands off the coast of Fujian Province (such as the Kinmen/Jinmen Islands and Matsu/Mazu Islands) from the scope of defense.

Then, the PLA suddenly launched an intense artillery bombardment of the Kinmen and Matsu islands on August 23, 1958. In the 46 days between the start of the bombardment and the PRC’s declaration of a unilateral ceasefire on October 6, the PLA launched a total of nearly 500,000 shells into the area around the Kinmen Islands, resulting in a total of 591 casualties for the ROC Army. However, the ROC held out against this attack, and the U.S. military supported the ROC Army while avoiding direct combat (Garver 1999, this chapter).

The war gradually became a stalemate. The U.S. military again seriously considered using nuclear weapons against the PRC. But the war between the two Chinese sides was more political. This time, the PLA’s offensive to capture the Kinmen and Matsu islands failed to achieve its goal. The PLA shelled on odd-numbered days, switching to leaflet projectiles and temporarily increasing its shelling when politically necessary. Gradually, the ROC Army began shelling on even-numbered days, and the ritualistic bombardment with blanks continued for about 20 years until the normalization of diplomatic relations between the United States and the PRC.

In July 1958, prior to the bombardment, Soviet Premier Nikita Khrushchev visited China and met with Mao Zedong, but despite being an ally, the Soviet Union was not informed of the planned bombardment. The distrust toward China that grew in the Soviet Union at that time became the fuse for the later confrontation between China and the Soviet Union.

U.S. Secretary of State John F. Dulles stated in the Joint Communiqué (the Dulles-Chiang Communiqué) immediately after the 1958 crisis that Chiang Kai-shek had supposedly abandoned counterattacks on the mainland. However, it was only because “the use of force” was not the “the principal means,” and Chiang Kai-shek did not give up counterattacks on the mainland (Garver 1999, this chapter).

In 1960, Chiang Kai-shek was elected to a third term, which was forbidden by the Constitution, and he continued to be president until his death in 1975, having been elected to a fifth term. Taiwanese society was caught up in the dream of Chiang Kai-shek and KMT to unite China, and the dark era of the White Terror and military mobilization continued.

4.3 The 1962 Crisis

Traditionally, the Taiwan Strait crisis has been regarded by the U.S. as a crisis of Taiwan’s defense and the accompanying possibility of military conflict with the PRC. In fact, many of the military conflicts over the Taiwan Strait were initiated by the ROC. In particular, in 1962 the ROC almost launched a large-scale counterattack on the mainland led by Chiang Kai-shek (Garver 1999, Chap. 6).

The failure of the Great Leap Forward policy (1958–60) and a long drought caused a serious calamity in the PRC, where more than 30 million people are said to have died of starvation. The PRC was plagued by troubles both at home and abroad. Internationally, the Sino-Soviet relationship was destabilized, and the Sino-Indian War broke out due to a border dispute. This was an opportunity for Chiang Kai-shek to make a move.

The ROC proposed launching a large-scale counterattack on the mainland to the U.S. and requested its support. The U.S. administration of John F. Kennedy was opposed to any large-scale counterattack that could have resulted in Soviet intervention but supported a small-scale attack to hold the ROC together. The 1962 counterattack on the mainland was a well-prepared move but was frustrated when the U.S. cleverly forestalled it, forcing the ROC to switch to small-scale guerilla warfare (Garver 1999, this chapter).

On the other hand, the PLA crushed the ROC Army’s assault in the southeast coastal region and also sank four ROC Navy ships. Furthermore, the PRC successfully conducted a nuclear test in October 1964, which made the ROC’s mainland counterattacks more and more hopeless. The ROC Navy was defeated in naval battles in 1965, forcing Chiang Kai-shek to adopt a passive policy of waiting for a good opportunity to launch a counterattack on the mainland.

Just as 1958 was a turning point in which Chiang Kai-shek was forced to realize that military action by the PRC could not change the status quo, 1965 was a turning point in which the ROC was forced to realize that counterattacks on the mainland were virtually impossible.

The ROC’s last attempt at a counterattack on the mainland was in 1967, when the ROC saw the Vietnam War as an “opportunity” and approached the Lyndon Johnson administration in the United States with a proposal for a counterattack on the mainland, which was rejected. The “extension” of the Chinese Civil War thus became unwinnable, and the diplomatic struggle for diplomatic recognition took center stage.

The extension of the Chinese Civil War also cast a large shadow on the internal affairs of the PRC and the ROC, respectively. In Taiwan, the hopeless dictatorship of Chiang Kai-shek continued, and his eldest son, Chiang Ching-kuo, took over the reins of power. In the PRC, the wartime regime in the coastal areas was maintained through military confrontation with the ROC on Taiwan.

Although the PRC unilaterally ceased fighting on New Year’s Day 1979, and the ROC unilaterally declared the end of the civil war in 1991, the hostilities between the PRC and the ROC on Taiwan have not strictly ended yet since no ceasefire agreement has even been signed.

However, the move away from civil war changed both the PRC and ROC on Taiwan. For the PRC, the normalization of diplomatic relations between the U.S. and PRC led by Deng Xiaoping after 1978, Taiwan’s peaceful reunification policy, and the Opening of the PRC were mutually complementary strategic packages. On the other hand, Taiwan’s democratization in later years politically empowered the native Taiwanese who made up the majority in Taiwanese society, which was an indirect factor in the deterioration of relations with the PRC and the improvement of relations with Japan.

5 Alliances in the Asia–Pacific

5.1 U.S. Security Treaties with Japan, the Philippines, Australian and New Zealand

Alliances in the Asia–Pacific region, like those in Europe, were a product of the Cold War. However, the basic conditions differed from those in Europe in two respects. First, as a result of the Asia–Pacific War, the United States was able to enjoy predominance in the Pacific region, in contrast to Europe where the Soviet Union’s massive land forces were barely balanced by U.S. nuclear capability. The other was the existence of Communist China, the only country other than Russia to achieve communist revolution. In George F. Kennan’s containment strategy, the continental part of Asia was not necessarily strategically important for the United States, and the basic policy was to secure and strengthen the island chain from the Aleutian Islands through the Japanese archipelago to Okinawa and the Philippines. Nevertheless, with the outbreak of the Korean War in June 1950 and Communist China’s entry into the war, the security of the southern Korean Peninsula was incorporated into the U.S. Cold War strategy, while the U.S.-China confrontation reached a point of no return. In addition to the Soviet Union, the challenge faced by the United States and other Western countries was how to reduce the authority and influence of the Chinese Communist Party in the Asia–Pacific region (Leffler 1992; Gaddis 2005).

The peace with Japan, pursued in the midst of the Korean War, constituted an integral part of the U.S. Cold War strategy to solidify the West. While welcoming Japan to the West through a generous peace treaty, the U.S. government decided to maintain and strengthen Japan’s security and U.S. strategic interests, specifically through the continued presence of U.S. armed forces in Japan after the Occupation, the long-term control of Okinawa, and Japanese rearmament. The Truman administration considered forming a regional collective security framework, the Pacific Pact, between non-Communist countries in the region, including Japan, the U.S., and other Western countries, which was supposed to position U.S. military bases in Japan as well as Japan’s self-defense capabilities as the measures to maintain peace and stability in the Asia Pacific. In other words, the United States expected that the regional collective security framework would simultaneously satisfy the security of Japan and the security against Japan.

The Pacific Pact failed to gain the support of the Commonwealth countries and Japan, and as a result, the United States concluded the U.S.-Japan Security Treaty, the U.S.-Philippines Mutual Defense Treaty, and the ANZUS Treaty from July to September 1951, respectively, along with the Peace Treaty with Japan. All three treaties were provisional arrangements pending the development of a more comprehensive system of regional security in the Pacific area. Japan and Okinawa, providing the largest U.S. bases, functioned to support the forward deployment of U.S. forces in the entire Asia–Pacific region. The Peace Treaty virtually guaranteed that the United States had the right to exercise all and any powers of administration, legislation, and jurisdiction over the territory and inhabitants of the Ryukyu Islands; from around 1953, the U.S. military began to coercively construct and expand bases in Okinawa. Meanwhile, for mainland Japan, the Security Treaty, the Administrative Agreement on the U.S. use of facilities and areas in Japan, and the Notes Exchanged between Prime Minister Yoshida Shigeru and Secretary of State Dean Acheson, legally allowed U.S. forces’ freedom of action in the Japanese region and the Far East. However, Japan’s dissatisfaction with the 1951 Security Treaty, which did not oblige the United States to defend Japan, and various base problems caused by the stationing of U.S. forces, constituted one of the factors that generated anti-U.S. sentiments among Japanese. Establishing the stable bilateral security relationship under the Security Treaty posed a major challenge for the United States throughout the 1950s (Kusunoki 2009, 2016; Miller 2019).

5.2 Mutual Defense Treaties in the Mid-1950s

The sequence of events from 1953 until 1954, from the Korean War Armistice Agreement, the 1954 Geneva Conference, the Geneva Accords, and the first Taiwan Strait crisis, created and entrenched divisions in Asia, which was accompanied by individual and multilateral mutual defense treaties between the United States and non-Communist countries in the Asia–Pacific region.

Although Stalin’s death in the spring of 1953 promoted armistice talks on the Korean War, President Syngman Rhee of the Republic of Korea (ROK) was negative about the armistice agreement, which did not ensure the security of Korea and preferred to conclude a mutual defense treaty with the United States beforehand. The Eisenhower administration decided to enter into negotiations with the ROK lest Rhee’s intransigence that would not rule out unilaterally using force might crumble the cease-fire. The two countries tentatively signed the U.S.-ROK Mutual Defense Treaty in Seoul (officially signed in Washington on October 1), while the ROK government agreed to cooperate in the implementation of the armistice agreement and to place South Korean forces under the operational control of UN military commanders.

The primary objective of the U.S.-ROK Mutual Defense Treaty was to maintain the armistice and prevent the recurrence of Communist attacks on the south. On the other hand, this treaty was limited to “territories now under their respective administrative control, or hereafter recognized by one of the Parties as lawfully brought under the administrative control of the other” (Article 3), which meant that the United States did not have the obligation to assist ROK if it attacked North Korea. As was the case with the ANZUS Treaty and the U.S.-Philippines Mutual Defense Treaty, the preamble to this treaty, stating that both countries desired to strengthen their efforts for collective defense “pending the development of a more comprehensive and effective system of regional security in the Pacific area,” showed that this treaty was envisioned to eventually function as part of a collective security system in the Asia–Pacific region. However, the immediate goal of the United States was to maintain and strengthen ROK’s position as the peaceful settlement of the Korean question became stalled (Stueck 1995; Sakata 2005).

As the Indochina peace process got underway in the spring–summer of 1954 in the midst of the Communist offensive, the Eisenhower administration considered more vigorous measures to strengthen defense capabilities of non-communist countries in the Asia–Pacific as well as building a regional security system in order to prevent Indochina from falling into Communists’ hands and reduce China’s influence in the region. After discussions led by the United States and the United Kingdom on the cooperation for regional security between Southeast Asian countries and the West, the Southeast Asia Collective Defense Treaty was signed in Manila on September 8, 1954. Each of the member states (the Philippines, Thailand, Pakistan, the United States, the United Kingdom, France, Australia, and New Zealand) of the newly established Southeast Asia Treaty Organization (SEATO) “recognizes that aggression by means of armed attack in the treaty area against any of the Parties or against any State or territory which the Parties by unanimous agreement may hereafter designate, would endanger its own peace and safety, and agrees that it will in that event act to meet the common danger in accordance with its constitutional processes” (Article 4.1). The treaty area was defined as “the general area of Southeast Asia, including also the entire territories of the Asian Parties,” and “the general area of the Southwest Pacific not including the Pacific area north of 21 degrees 30 min north latitude” (Article 8), which meant that non-member states, such as Indochinese countries, might be included in the treaty area. It was also designed to allow for the expansion of membership in the future.

SEATO gradually constructed its institutions and procedures throughout the 1950s, and advanced cooperation among member countries through meeting challenges such as economic development or the improvement of the ability to counter Communist subversion. The U.S. government emphasized SEATO’s greatest role to draw a line which, if crossed, would permit the member states to retaliate at the source of aggression and to do so with the support of other nations; it did not envision itself obligated to provide large-scale military or economic assistance to Asian countries or to deploy U.S. armed forces for the purpose of territorial defense in Southeast Asia. Furthermore, the member countries did not always share common interests. When the political situation in Laos got destabilized in the late 1950s and early 1960s, they were at odds over intervention, consequently leading SEATO’s failure to undertake coordinated actions (Nishida 2016; Terachi 2021).

Taiwan became a focal point in the post-Indochina region as Communist China intensified its offensive against the KMT government through seizing island areas in the Taiwan Strait under Nationalist China’s control around the spring of 1954. The formation of SEATO raised concerns that the KMT government, to which the U.S. had no treaty obligations, would be isolated in Asia. In September, the Peking government launched a massive bombardment of Kinmen Island. The U.S. government was inclined to conclude a mutual defense treaty with the KMT government for reassurance and deterrence, while avoiding escalation of the crisis. The Mutual Defense Treaty between the United States and the Republic of China, signed on December 2, provided that both countries “recognize that an armed attack in the West Pacific area directed against the territories of either of the Parties would be dangerous to its own peace and safety and declares that it would act to meet the common danger in accordance with its constitutional processes” (Article 5). The treaty was supposed to be applied to Taiwan and the Pescadores, the island territories in the West Pacific under U.S. jurisdiction, and “such other territories as may be determined by mutual agreement” (Article 6). Both Kinmen and Matsu, areas validly under KMT control, were understood to be “such other territories,” but the KMT’s use of force in those areas was subject to consultation except in case of emergency, and the United States would not have the obligation to defend the Republic of China if it would resort to military actions beyond its territories without consultation. In other words, this Mutual Defense Treaty was given a dual function: the deterrence against Communist China and the prevention of ROC’s attack on the mainland. Through the first Taiwan Strait Crisis and the conclusion of the U.S.-ROC Mutual Defense Treaty, the U.S. government confirmed military capability and the will of the Communist regime, inevitably pursuing the “two Chinas” policy (Tucker 1994a, b; Accinelli 1996; Matsumoto 1998).

While promoting bilateral or multilateral security frameworks with the United States as one party, the Eisenhower administration maintained the goal to establish a regional collective security system encompassing Northeast Asia and Southeast Asia. The ROK, the Philippines, and the ROC also presented various visions of the cooperative security framework among non-communist countries in the region. Nevertheless, the NATO-type comprehensive regional collective security organization has never been realized in the Asia–Pacific region. Three factors should be mentioned. First, there was a deep-seated anti-Japanese sentiment in Asian countries, particularly in South Korea and the Philippines. Reconciliation between Japan and its neighboring countries slowly progressed through sluggish negotiations on reparations between Japan and Southeast Asian countries as well as on the normalization of diplomatic relations between Japan and ROK. Second, U.S. strategic interests were not necessarily shared with the countries concerned. The U.S. government expected to develop the defense capabilities of Asian countries to counter the Communist threat, but Japan, in particular, neither developed its self-defense forces at the scale and speed that the U.S. had hoped for, nor had little intention to contribute to the security of the entire region. Many countries in the region were expecting to obtain Western economic assistance through regional cooperation. The degree to which the situation in the Taiwan Strait or Indochina was linked to their own security interests was not always the same, which impeded the Western countries in the region from reaching a consensus on collective defense.

Third, relations between European countries and newly independent Asian countries were also strained. Although the United Kingdom and France were indispensable to peace and stability in Southeast Asia as former colonial rulers with grave influence and interests in the region, their actions were perceived as colonialism by Asian countries and provoked opposition. In confused situations associated with nation-building processes in which nationalist movements driven by strong anti-colonialism directly or indirectly had connection with communist forces, it was not easy to identify “communist forces” as a threat. Many countries in the Asia–Pacific were eventually inclined to maintain and enhance their security relationships with the United States throughout the 1950s.

5.3 Communist Alliances

Security cooperation among Communist powers in Asia also took the form of a cluster of bilateral agreements. The Soviet Union and Communist China established mutual assistance in February 1950, followed by agreements between North Korea and other two powers in July 1961, respectively.

As it became clear that the Chinese Communist Party (CCP) would prevail in the Sino-Communist Civil War around the fall of 1948, relations between the Soviet Union and the CCP deepened. The cognitive framework of Mao Zedong and CCP leaders, based on revolutionary theory and their fundamental attitude to the growth in international tensions at that time, largely influenced CCP policy, propelling Mao’s concept of “leaning to one side” into the basic tendency and choice of the CCP’s leaders. After a series of secret talks and negotiations between the leaders, Mao visited Moscow in December 1949 and, finally, achieved the Sino-Soviet Friendship and Alliance Mutual Assistance Treaty on February 14. Both countries were supposed to “immediately extend military and other assistance with all the means at its disposal,” if either of them was attacked by “Japan or by States allied with Japan” (Article 1). The treaty was explicitly against Japan and the United States, on the basis of which the Soviet Union initiated economic, financial, and military assistance to China. The establishment of the People’s Republic of China and its close relationship with the Soviet Union became the decisive factors that resulted in the Japanese government abandoning the idea of peace with all Allied countries. And the Korean War and the Chinese Volunteer Army’s participation in strengthened the Sino-Soviet alliance through demonstrating the CCP’s loyalty to the Soviet Union and the socialist camp.

While promising mutual assistance, the Treaty also reflected the power differential between China and the Soviet Union at the time. The Sino-Soviet Friendly Alliance Treaty between the Kuomintang regime and the Soviet Union in August 1945 was to expire with the establishment of the new Sino-Soviet Treaty in 1950; however, both countries agreed that the Changchun Railway and the naval base at Port Arthur was to be handed over to PRC, and the treatment of Dalian would be decided only after the conclusion of the peace treaty with Japan, which was envisioned around 1952. Moreover, the supplementary agreement on Northeastern China and Xinjiang stipulated that foreigners would be prohibited from owning management rights, or the activities of industrial, financial, commercial, and other enterprises, institutions, companies, and organizations in which third countries other than China and the Soviet Union and their citizens participated and invested in a direct or indirect manner would not be permitted. Mao Zedong, longing for Soviet military aid, accepted this Soviet request as a secret agreement. In addition to disagreements over Hong Kong and Taiwan, these issues suggested that the Sino-Soviet alliance was fraught with tension (Westad 1998; Chen 2001; Qing 2007).

North Korea had no formal treaties of an alliance nature with the Soviet Union as well as with China throughout the 1950s. The Soviet Union had almost complete control over North Korea; both China and North Korea were theoretically revolutionary regimes with identical principles, but in reality, they were independent ethnic groups whose cooperation was tense. Because both were in a position to look to Moscow for guidance, there were few direct inter-institutional channels between the two. China, however, backed by the close Sino-Soviet relationship, secured the initiative in the strategy and tactics of the Korean War, which instilled a sense of frustration in North Korea since they had no choice but to follow the CCP (Shen 2016).

The gradually escalated rivalry between China and the Soviet Union in the late 1950s increased North Korea’s importance to both countries. After the complete withdrawal of Chinese troops from Korea in October 1958, Kim Il Sung, fearing an imbalance of military power between North and South Korea, requested a treaty of friendship, cooperation, and mutual assistance from the Soviet Union in January of the following year. While Chairman Nikita S. Khrushchev pursued the improvement of relations with the United States, the PRC moved toward building relations with North Korea and other communist countries, driven by tensions in China’s periphery that began around the summer of 1958—the second Taiwan Strait Crisis, the border dispute with India, and the fears of a fluid situation in Vietnam. In November 1959, China agreed to military aid with North Korea.

When the Sino-Soviet confrontation became more decisive in the summer of 1960, both countries offered economic and technical assistance, loans, and trade agreements to win over North Korea to their side. In July 1961, Kim Il Sung visited Moscow and succeeded in concluding the Treaty of Friendship, Cooperation, and Mutual Assistance with the Soviet Union. On his way back, he visited Beijing and concluded an almost identical treaty with the PRC. The two treaties stipulated mutual defense a prohibition on the formation of hostile alliances, or the principles of mutual respect for sovereignty, non-interference in each other’s internal affairs, equality and mutual benefit and in the spirit of friendly cooperation, with both the Soviet Union and China each assuming defense obligations toward the DPRK. The only significant difference was the validity period. While the Soviet-DPRK treaty was valid for a period of 10 years, the Sino-DPRK treaty would remain in force until the contracting parties agreed on its amendment or termination. This meant that China assumed a stricter and more permanent obligation with regard to North Korea’s security (Lüthi 2006; Shen 2016).

North Korea took advantage of the Sino-Soviet confrontation to extract maximum benefits from both sides in the form of aid and security. Through equidistant diplomacy toward the PRC and Soviet Union, Kim Il Sung further strengthened his political position within the Workers’ Party of Korea as well as the DPRK. The presence of Communist China, an independent “great power” that had succeeded in revolution, was a major factor in shaping the Cold War structure and alliances in the Asia–Pacific region differently from those in Europe. On the other hand, while the alliances between the U.S. and the West in the Asia–Pacific region were strengthened and served as a basis for coordinating bilateral relations, the individual alliances among three Communist countries in Northeast Asia did not necessarily serve as a basis for bilateral relations.