Foreign policy of the Harry S. Truman administration

When Truman took office, several international organizations that were designed to help prevent future wars and international economic crises were in the process of being established.[14] Chief among those organizations was the United Nations, an intergovernmental organization similar to the League of Nations that was designed to help ensure international cooperation.[31] When Truman took office, delegates were about to meet at the United Nations Conference on International Organization in San Francisco.[32] As a Wilsonian internationalist, Truman strongly supported the creation of the United Nations, and he signed United Nations Charter at the San Francisco Conference. Truman did not repeat Woodrow Wilson's partisan attempt to ratify the Treaty of Versailles in 1919, instead cooperating closely with Senator Arthur H. Vandenberg and other Republican leaders to ensure ratification. Cooperation with Vandenberg, a leading figure on the Senate Foreign Relations Committee, would be crucial for Truman's foreign policy, especially after Republicans gained control of Congress in the 1946 elections.[33][34] Construction of the United Nations headquarters in New York City was funded by the Rockefeller Foundation and completed in 1952.

In 1934, Congress had passed the Reciprocal Tariff Act, giving the president an unprecedented amount of authority in setting tariff rates. The act allowed for the creation of reciprocal agreements in which the U.S. and other countries mutually agreed to lower tariff rates.[35] Despite significant opposition from those who favored higher tariffs, Truman was able to win legislative extension of the reciprocity program, and his administration reached numerous bilateral agreements that lowered trade barriers.[36] The Truman administration also sought to further lower global tariff rates by engaging in multilateral trade negotiations, and the State Department proposed the establishment of the International Trade Organization (ITO). The ITO was designed to have broad powers to regulate trade among member countries, and its charter was approved by the United Nations in 1948. However, the ITO's broad powers engendered opposition in Congress, and Truman declined to send the charter to the Senate for ratification. In the course of creating the ITO, the U.S. and 22 other countries signed the General Agreement on Tariffs and Trade (GATT), a set of principles governing trade policy. Under the terms of the agreement, each country agreed to reduce overall tariff rates and to treat each co-signatory as a "most favoured nation," meaning that no non-signatory country could benefit from more advantageous tariff rates. Due to a combination of the Reciprocal Tariff Act, the GATT, and inflation, U.S. tariff rates fell dramatically between the passage of the Smoot–Hawley Tariff Act in 1930 and the end of the Truman administration in 1953.[35]

World War II left millions of refugees displaced in Europe. To help address this problem, Truman backed the founding of the International Refugee Organization (IRO), a temporary international organization that helped resettle refugees.[37] The United States also funded temporary camps and admitted large numbers of refugees as permanent residents. Truman obtained ample funding from Congress for the Displaced Persons Act of 1948, which allowed many of the displaced people of World War II to immigrate into the United States.[38] Of the approximately one million people resettled by the IRO, more than 400,000 settled in the United States. The most contentious issue facing the IRO was the resettlement of European Jews, many of whom, with the support of Truman, were allowed to immigrate to British-controlled Mandatory Palestine.[37] The administration also helped create a new category of refugee, the "escapee," at the 1951 Geneva Convention Relating to the Status of Refugees. The American Escapee Program began in 1952 to help the flight and relocation of political refugees from communism in Eastern Europe. The motivation for the refugee and escapee programs was twofold: humanitarianism, and use as a political weapon against inhumane communism.[39]

In March 1946, at an optimistic moment for postwar cooperation, the administration released the Acheson-Lilienthal Report, which proposed that all nations voluntarily abstain from constructing nuclear weapons. As part of the proposal, the U.S. would dismantle its nuclear program once all other countries agreed not to develop or otherwise acquire nuclear weapons. Fearing that Congress would reject the proposal, Truman turned to the well-connected Bernard Baruch to represent the U.S. position to the United Nations. The Baruch Plan, largely based on the Acheson-Lilienthal Report, was not adopted due to opposition from Congress and the Soviet Union. The Soviet Union would develop its own nuclear arsenal, testing a nuclear weapon for the first time in August 1949.[40]

The United States Atomic Energy Commission, directed by David E. Lilienthal until 1950, was in charge of designing and building nuclear weapons under a policy of full civilian control. The U.S. had only 9 atomic bombs in 1946, but the stockpile grew to 650 by 1951.[41] Lilienthal wanted to give high priority to peaceful uses for nuclear technology, especially nuclear power plants, but coal was cheap and the power industry was largely uninterested in building nuclear power plants during the Truman administration. Construction of the first nuclear plant would not begin until 1954.[42] In early 1950, Truman authorized the development of thermonuclear weapons, a more powerful version of atomic bombs. Truman's decision to develop thermonuclear weapons faced opposition from many liberals and some government officials, but he believed that the Soviet Union would likely develop the weapons and was unwilling to allow the Soviets to have such an advantage.[43] The first test of thermonuclear weaponry was conducted by the United States in 1952; the Soviet Union would perform its own thermonuclear test in August 1953.[44]

Following World War II, the United States, France, Britain, and the Soviet Union each took control of occupation zones in Germany and the German capital of Berlin

The Second World War dramatically upended the international system, as formerly-powerful nations like Germany, France, Japan, and even Britain had been devastated. At the end of the war, only the United States and the Soviet Union had the ability to exercise influence, and a bipolar international power structure replaced the multipolar structure of the Interwar period.[45] On taking office, Truman privately viewed the Soviet Union as a "police government pure and simple," but he was initially reluctant to take a hard-line towards the Soviet Union, as he hoped to work with the Soviets in the aftermath of Second World War.[46] Truman's suspicions deepened as the Soviets consolidated their control in Eastern Europe throughout 1945, and the February 1946 announcement of the Soviet five-year plan further strained relations as it called for the continuing build-up of the Soviet military.[47] At the December 1945 Moscow Conference, Secretary of State Byrnes agreed to recognize the pro-Soviet governments in the Balkans, while the Soviet leadership accepted U.S. leadership in the occupation of Japan. U.S. concessions at the conference angered other members of the Truman administration, including Truman himself.[48] By the beginning of 1946, it had become clear to Truman that Britain and the United States would have little influence in Soviet-dominated Eastern Europe.[49]

Former Vice President Henry Wallace, former First Lady Eleanor Roosevelt, and many other prominent Americans continued to hope for cooperative relations with the Soviet Union.[50] Some liberals, like Reinhold Niebuhr, distrusted the Soviet Union but believed that the United States should not try to counter Soviet influence in Eastern Europe, which the Soviets saw as their "strategic security belt."[51] Partly because of this sentiment, Truman was reluctant to fully break with the Soviet Union in early 1946,[50] but he took an increasingly hard line towards the Soviet Union throughout the year.[52] He personally approved of Winston Churchill's March 1946 "Iron Curtain" speech, which urged the United States to take the lead of an anti-Soviet alliance, though he did not publicly endorse it.[50]

Throughout 1946, tensions arose between the United States and the Soviet Union in places like Iran, which the Soviets had occupied during World War II. Pressure from the U.S. and the United Nations finally forced the withdrawal of Soviet soldiers.[53] Turkey also emerged as a point of contention, as the Soviet Union demanded joint control over the Dardanelles and the Bosphorus, key straits that controlled movement between the Black Sea and the Mediterranean Sea. The U.S. forcefully opposed this proposed alteration to the 1936 Montreux Convention, which had granted Turkey sole control over the straits, and Truman dispatched a fleet to the Eastern Mediterranean to show his administration's commitment to the region.[54] The Soviet Union and the United States also clashed in Germany, which had been divided into four occupation zones. In the September 1946 Stuttgart speech, Secretary of State Byrnes announced that the United States would no longer seek reparations from Germany and would support the establishment of a democratic state. The United States, France, and Britain agreed to combine their occupation zones, eventually forming West Germany.[55] In East Asia, Truman denied the Soviet request to reunify Korea, and refused to allow the Soviets a role in the post-war occupation of Japan.[56]

By September 1946, Truman was convinced that the Soviet Union sought world domination and that cooperation was futile.[57] He adopted a policy of containment, based on a 1946 cable by diplomat George F. Kennan.[58] Containment, a policy of preventing the further expansion of Soviet influence, represented a middle-ground position between friendly detente (as represented by Wallace), and aggressive rollback to regain territory already lost to Communism, as would be adopted in 1981 by Ronald Reagan.[59] Kennan's doctrine was based on the notion that the Soviet Union was led by an uncompromising totalitarian regime, and that the Soviets were primarily responsible for escalating tensions.[60] Wallace, who had been appointed Secretary of Commerce after the 1944 election, resigned from the cabinet in September 1946 due to Truman's hardening stance towards the Soviet Union.[61]

In the first major step in implementing containment, Truman extended loans to Greece and Turkey to prevent the spread of Soviet-aligned governments.[62] Prior to 1947, the U.S. had largely ignored Greece, which had an anti-communist government, because it was under British influence.[63] Since 1944, the British had assisted the Greek government against a left-wing insurgency, but in early 1947 the British informed the United States that they could no longer afford to intervene in Greece. At the urging of Acheson, who warned that the fall of Greece could lead to the expansion of Soviet influence throughout Europe, Truman requested that Congress grant an unprecedented $400 million aid package to Greece and Turkey. In a March 1947 speech before a joint session of Congress, written by Acheson, Truman articulated the Truman Doctrine. It called for the United States to support "free people who are resisting attempted subjugation by armed minorities or by outside pressures." Overcoming isolationists who opposed involvement in Greek affairs, as well on the left who wanted cooperation with Moscow, Truman won bipartisan approval of the aid package.[64] The congressional vote represented a permanent break with the non-interventionism that had characterized U.S. foreign policy prior to World War II.[65]

The United States became closely involved in the Greek Civil War, which ended with the defeat of the insurgency in 1949. Stalin and Yugoslavian leader Josip Broz Tito both provided aid to the insurgents, but they fought for control causing a split in the Communist bloc.[66] American military and economic aid to Turkey also proved effective, and Turkey avoided a civil war.[67][68] The Truman administration also provided aid to the Italian government in advance of the 1948 general election where the Communists had strength. The aid package, combined with a covert CIA operation, anti-Communist mobilization by the Catholic Church and Italian Americans, helped to produce a Communist defeat.[69] The initiatives of the Truman Doctrine solidified the post-war division between the United States and the Soviet Union, and the Soviet Union responded by tightening its control over Eastern Europe.[70] Countries aligned with the Soviet Union became known as the Eastern Bloc, while the U.S. and its allies became known as the Western Bloc.

Although the far left element in the Democratic Party and the CIO was being expelled, some liberal Democrats opposed the Truman Doctrine. Eleanor Roosevelt wrote Truman in April 1947 calling him to rely on the United Nations instead of his Truman Doctrine. She denounced two Greece and Turkey because they were undemocratic and complained he was adopting “Mr. Churchill’s policies in the Near East.” Truman needed support from the Roosevelt wing, wrote her that while he held onto his long-term hopes for the United Nations, he insisted that and an "economically, ideologically and politically sound" peace would more likely come from American action, than from the United Nations. He emphasized the strategic geographical importance of the Greek-Turkish land bridge as a critical point in which democratic forces could stop the advance of communism that had so ravaged Eastern Europe.[71]

Facing new, global challenges, the Truman administration reorganized the military and intelligence establishment to provide for more centralized control and reduce rivalries.[7] The National Security Act of 1947 combined and reorganized all military forces by merging the Department of War and the Department of the Navy into the National Military Establishment (which was later renamed as the Department of Defense). The law also created the U.S. Air Force, the Central Intelligence Agency (CIA), and the National Security Council (NSC). The CIA and the NSC were designed to be non-military, advisory bodies that would increase U.S. preparation against foreign threats without assuming the domestic functions of the Federal Bureau of Investigation.[73] The National Security Act institutionalized the Joint Chiefs of Staff, which had been established on a temporary basis during World War II. The Joint Chiefs of Staff took charge of all military action, and the Secretary of Defense became the chief presidential adviser on military matter. In 1952, Truman secretly consolidated and empowered the cryptologic elements of the United States by creating the National Security Agency (NSA).[74] Truman also sought to require one year of military service for all young men physically capable of such service, but this proposal never won more than modest support among members of Congress.[75]

Truman had hoped that the National Security Act would minimize interservice rivalries, but each branch retained considerable autonomy and battles over the military budgets and other issues continued.[76] In 1949, Secretary of Defense Louis Johnson announced that he would cancel a so-called "supercarrier," which many in the navy saw as an important part of the service's future.[77] The cancellation sparked a crisis known as the "Revolt of the Admirals", when a number of retired and active-duty admirals publicly disagreed with the Truman administration's emphasis on less expensive strategic atomic bombs delivered by the air force. During congressional hearings, public opinion shifted strongly against the navy, which ultimately kept control of marine aviation but lost control over strategic bombing. Military budgets following the hearings prioritized the development of air force heavy bomber designs, and the United States accumulated a combat ready force of over 1,000 long-range strategic bombers capable of supporting nuclear mission scenarios.[78]

Following the end of World War II, Truman gave a low priority to defense budgets—it got whatever money was left over after domestic spending. From the beginning, he assumed that the American monopoly on the atomic bomb was adequate protection against any and all external threats.[79] Military spending plunged from 39% of GNP in 1945 to only 5% in 1948.[80] The number of military personnel fell from just over 3 million in 1946 to approximately 1.6 million in 1947, although the number of military personnel was still nearly five times larger than that of U.S. military in 1939.[81] In 1949, Truman ordered a review of U.S. military policies in light of the Soviet Union's acquisition of nuclear weapons. The National Security Council drafted NSC 68, which called for a major expansion of the U.S. defense budget, increased aid to U.S. allies, and a more aggressive posture in the Cold War. Despite increasing Cold War tensions, Truman dismissed the document, as he was unwilling to commit to higher defense spending.[82] The Korean War convinced Truman of the necessity for higher defense spending, and such spending would soar between 1949 and 1953.[83]

Marshall Plan expenditures by country

The Marshall Plan was launched by the United States in 1947-48 to replace numerous ad hoc loan and grant programs, with a unified, long-range plan to help restore the European economy, modernize it, remove internal tariffs and barriers, and encourage European collaboration. It was funded by the Republican -controlled Congress, where the isolationist Republican element was overwhelmed by a new internationalism. Stalin refused to let any of his satellite nations in Eastern Europe participate. Much less famous was a similar aid program aimed at Japan, China and other Asian countries. All the money was donated – there was no repayment needed. (At the same time, however, There were US government loan programs that did require repayment.)[84]

The United States had suddenly terminated the war-time Lend-Lease program in August 1945, to the surprise and distress of Britain, the Soviet Union and other nations. However the United States did send large sums and loans and relief supplies, though in an uncoordinated fashion with no long-term plan.[85] Western Europe was slowly recovering by 1947; Eastern Europe was being stripped of its resources by Moscow. Churchill warned that Europe was "a rubble heap, a charnel house, a breeding ground for pestilence and hate." American leaders feared that poor economic conditions could lead to Communism in France and Italy, where the far left was under Stalin's control. With the goal of containing Communism and increasing trade between the U.S. and Europe, the Truman administration devised the Marshall Plan. Dean Acheson was the key planner, But Marshall's an enormous worldwide prestige was used to sell the program at home and abroad. It sought to rejuvenate, Coordinate and modernize the economies of Europe. The Kremlin forced its satellites to reject Marshall Plan aid.[86] To fund the Marshall Plan, Truman asked Congress to approve an unprecedented, multi-year, $25 billion appropriation.[87] Congress, under the control of conservative Republicans, agreed to fund the program for multiple reasons. The 20-member conservative isolationist wing of the Republican Party, based in the rural Midwest, was led by Senator Kenneth S. Wherry. Wherry argued that it would be "a wasteful 'operation rat-hole'"; that it made no sense to oppose communism by supporting the socialist governments in Western Europe; and that American goods would reach Russia and increase its war potential. The isolationist bloc opposed loans or financial aid of any sort to Europe, opposed NATO, and tried to void presidential power to send troops to Europe. Their political base included many German-American and Scandinavian American communities that had suffered nasty attacks on their American patriotism during World War I. No matter what the issue, they could be counted on as vocal enemies of the Truman administration.[88] Wherry was outmaneuvered by the emerging internationalist wing in the Republican Party, led by Michigan Senator Arthur H. Vandenberg.

With support from Republican Senator Henry Cabot Lodge, Jr., Vandenberg admitted there was no certainty that the plan would succeed, but said it would halt economic chaos, sustain Western civilization, and stop further Soviet expansion.[89] Senator Robert A. Taft, a leading conservative Republican who was generally skeptical of American commitments in Europe, chose to focus on domestic issues and deferred to Vandenberg on foreign policy.[90] Major newspapers were highly supportive, including pro-business conservative outlets like Time Magazine.[91][92] Both houses of Congress approved the initial appropriation, known as the Foreign Assistance Act, by large majorities, and Truman signed the act into law in April 1948.[93] Congress would eventually allocate $12.4 billion in aid over the four years of the plan.[94]

A new Washington agency the European Recovery Program (ERP) ran the Marshall Plan and close cooperation with the recipient nations. The money proved decisive, but the ERP was focused on a longer-range vision that included more efficiency, more high technology, and the removal of multiple internal barriers and tariffs inside Western Europe. ERP allowed each recipient to develop its own plan for the aid, it set several rules and guidelines on the use of the funding. Governments were required to exclude Communists, socialist policies were allowed, and balanced budgets were favored. Additionally, the ERP conditioned aid to the French and British on their acceptance of the reindustrialization of Germany and support for European integration. The Soviets set up their own program for aid, the Molotov Plan, and the new barriers reduced trade between the Eastern bloc and the Western bloc.[95]

The Marshall Plan helped European economies recover in the late 1940s and early 1950s. By 1952, industrial productivity had increased by 35 percent compared to 1938 levels. The Marshall Plan also provided critical psychological reassurance to many Europeans, restoring optimism to a war-torn continent. Though European countries did not adopt American economic structures and ideas to the degree hoped for by some Americans, they remained firmly rooted in mixed economic systems. The European integration process led to the creation of the European Economic Community, which eventually formed the basis of the European Union.[96]

In reaction to Western moves aimed at reindustrializing their German occupation zones, Stalin ordered a blockade of the Western-held sectors of Berlin, which was deep in the Soviet occupation zone. Stalin hoped to prevent the creation of a western German state aligned with the U.S., or, failing that, to consolidate control over eastern Germany.[97] After the blockade began on June 24, 1948, the commander of the American occupation zone in Germany, General Lucius D. Clay, proposed sending a large armored column across the Soviet zone to West Berlin with instructions to defend itself if it were stopped or attacked. Truman believed this would entail an unacceptable risk of war, and instead approved Ernest Bevin's plan to supply the blockaded city by air. On June 25, the Allies initiated the Berlin Airlift, a campaign that delivered food and other supplies, such as coal, using military aircraft on a massive scale. Nothing like it had ever been attempted before, and no single nation had the capability, either logistically or materially, to accomplish it. The airlift worked, and ground access was again granted on May 11, 1949. The Berlin Airlift was one of Truman's great foreign policy successes, and it significantly aided his election campaign in 1948.[98]

Map of NATO and the Warsaw Pact (which was created in 1955). The original NATO members are shaded dark blue.

Rising tensions with the Soviets, along with the Soviet veto of numerous United Nations Resolutions, convinced Truman, Senator Vandenberg, and other American leaders of the necessity of creating a defensive alliance devoted to collective security.[99] In 1949, the United States, Canada, and several European countries signed the North Atlantic Treaty, creating a trans-Atlantic military alliance and committing the United States to its first permanent alliance since the 1778 Treaty of Alliance with France.[100] The treaty establishing NATO was widely popular and easily passed the Senate in 1949. NATO's goals were to contain Soviet expansion in Europe and to send a clear message to communist leaders that the world's democracies were willing and able to build new security structures in support of democratic ideals. The treaty also re-assured France that the United States would come to its defense, paving the way for continuing French cooperation in the re-establishment of an independent German state. The U.S., Britain, France, Italy, the Netherlands, Belgium, Luxembourg, Norway, Denmark, Portugal, Iceland, and Canada were the original treaty signatories.[101] Shortly after the creation of NATO, Truman convinced Congress to pass the Mutual Defense Assistance Act, which created a military aid program for European allies.[102]

Cold War tensions heightened following Soviet acquisition of nuclear weapons and the beginning of the Korean War. The U.S. increased its commitment to NATO, invited Greece and Turkey to join the alliance, and launched a second major foreign aid program with the passage of the Mutual Security Act. Truman permanently stationed 180,000 in Europe, and European defense spending grew from 5 percent to 12 percent of gross national product. NATO established a unified command structure, and Truman appointed General Dwight D. Eisenhower as the first Supreme Commander of NATO. West Germany, which fell under the aegis of NATO, would eventually be incorporated into NATO in 1955.[103]

Truman usually worked well with his top advisors--the exceptions were Israel in 1948 and Spain 1945-50. Truman was a very strong opponent of Francisco Franco, the right-wing dictator of Spain. He withdrew the American ambassador (but diplomatic relations were not formally broken), kept Spain out of the UN, and rejected any Marshall Plan financial aid to Spain. However, as the Cold War escalated, support for Spain was strong in Congress, the Pentagon, the business community and other influential elements especially Catholics and cotton growers. Liberal opposition to Spain had faded after the Wallace element broke with the Democratic Party in 1948; the CIO became passive on the issue. As Secretary of State Acheson increased his pressure on Truman, the president, stood alone in his administration as his own top appointees wanted to normalize relations. When China entered the Korean War and pushed American forces back, the argument for allies became irresistible. Admitting that he was "overruled and worn down," Truman relented and sent an ambassador and made loans available. Military talks began and President Eisenhower later brought Spain into NATO.[104]

President Truman in the Oval Office, receiving a Hanukkah Menorah from the Prime Minister of Israel, David Ben-Gurion (center). To the right is Abba Eban, Ambassador of Israel to the U.S.

Truman had long taken an interest in the history of the Middle East, and was sympathetic to Jews who sought a homeland in British-controlled Mandatory Palestine. In 1943, he had called for a homeland for those Jews who survived the Nazi regime. However, State Department officials were reluctant to offend the Arabs, who were opposed to the establishment of a Jewish state in the region. Secretary of Defense Forrestal warned Truman of the importance of Saudi Arabian oil in another war; Truman replied that he would decide his policy on the basis of justice, not oil. American diplomats with experience in the region were opposed, but Truman told them he had few Arabs among his constituents.[107] Regarding policy in the Eastern Mediterranean and the Middle East, Palestine was secondary to the goal of protecting the "Northern Tier" of Greece, Turkey, and Iran from communism.[108]

In 1947, the United Nations approved the partition of Mandatory Palestine into a Jewish state and an Arab state. The British announced that they would withdraw from Palestine in May 1948, and Jewish leaders began to organize a provisional government. In the months leading up to the British withdrawal, the Truman administration debated whether or not to recognize the fledgling state of Israel. Overcoming initial objections from Marshall, Clark Clifford convinced Truman that non-recognition would lead Israel to tilt towards the Soviet Union in the Cold War.[109] Truman recognized the State of Israel on May 14, 1948, eleven minutes after it declared itself a nation.[110] Israel would secure its independence with a victory in the 1948 Arab–Israeli War, but the Arab–Israeli conflict remains unresolved.[111]

Following the defeat of the Empire of Japan, China descended into a civil war. The civil war baffled Washington, as both the Nationalists under Chiang Kai-shek and the Communists under Mao Zedong had American advocates.[112] Truman sent George Marshall to China in early 1946 to broker a compromise featuring a coalition government. The mission failed, as both sides felt the issue would be decided on the battlefield, not at a conference table. Marshall returned to Washington in December 1946, blaming extremist elements on both sides.[113] In mid-1947, Truman sent General Albert Coady Wedemeyer to China to try again, but no progress was made.[114][115]

Though the Nationalists held a numerical advantage in the aftermath of the war, the Communists gained the upper hand in the civil war after 1947. Corruption, poor economic conditions, and poor military leadership eroded popular support for the Nationalist government, and the Communists won many peasants to their side. As the Nationalists collapsed in 1948, the Truman administration faced the question of whether to intervene on the side of the Nationalists or seek good relations with Mao. Chiang's strong support among sections of the American public, along with desire to assure other allies that the U.S. was committed to containment, convinced Truman to increase economic and military aid to the Nationalists. However, Truman held out little hope for a Nationalist victory, and he refused to send U.S. soldiers.[116]

In 1949 Mao Zedong and his Communists took control of the mainland of China, driving the Nationalists to Taiwan. The United States had a new enemy in Asia, and Truman came under fire from conservatives for "losing" China.[117] Along with the Soviet detonation of a nuclear weapon, the Communist victory in the Chinese Civil War played a major role in escalating Cold War tensions and U.S. militarization during 1949.[118] Truman would have been willing to maintain some relationship between the U.S. and the Communist government, but Mao was unwilling.[119] Chiang established the Republic of China on Taiwan, which retained China's seat on the UN Security Council until 1971.[120][121][lower-alpha 1] In June 1950, after the outbreak of fighting in Korea, Truman ordered the Navy's Seventh Fleet into the Taiwan Strait to prevent further conflict between the communist government and the Republic of China.[122]

Under the leadership of General Douglas MacArthur, the U.S. occupied Japan after the latter's surrender in August 1945. MacArthur presided over extensive reforms of the Japanese government and society, implementing a new constitution that established a parliamentary democracy and granted women the right to vote. He also reformed the Japanese educational system and oversaw major economic changes, although Japanese business leaders were able to resist the reforms to some degree. As the Cold War intensified in 1947, the Truman administration took greater control over the occupation, ending Japanese reparations to the Allied Powers and prioritizing economic growth over long-term reform. The Japanese suffered from poor economic conditions until the beginning of the Korean War, when U.S. purchases stimulated growth.[123] In 1951, the United States and Japan signed the Treaty of San Francisco, which restored Japanese sovereignty but allowed the United States to maintain bases in Japan.[124] Over the opposition of the Soviet Union and some other adversaries of Japan in World War II, the peace treaty did not contain punitive measures such as reparations, though Japan did lose control of the Kuril Islands and other pre-war possessions.[125]

With the end of World War II, the United States fulfilled the commitment made by the 1934 Tydings–McDuffie Act and granted independence to the Philippines. The U.S. had encouraged decolonization throughout World War II, but the start of the Cold War changed priorities. The U.S. used the Marshall Plan to pressure the Dutch to grant independence to Indonesia under the leadership of the anti-Communist Sukarno, and the Dutch recognized Indonesia's independence in 1949. However, in French Indochina, the Truman administration recognized the French client state led by Emperor Bảo Đại. The U.S. feared alienating the French, who occupied a crucial position on the continent, and feared that the withdrawal of the French would allow the Communist faction of Ho Chi Minh to assume power.[126] Despite initial reluctance to become involved in Indochina, by 1952, the United States was heavily subsidizing the French suppression of Ho's Việt Minh in the First Indochina War.[83] The U.S. also established alliances in the region through the creation of the Mutual Defense Treaty with the Philippines and the ANZUS pact with Australia and New Zealand.[127]

President Truman signing a proclamation declaring a national emergency and authorizing U.S. entry into the Korean War

Following World War II, the United States and the Soviet Union occupied Korea, which had been a colony of the Japanese Empire. The 38th parallel was chosen as a line of partition between the occupying powers since it was approximately halfway between Korea's northernmost and southernmost regions, and was always intended to mark a temporary separation before the eventual reunification of Korea.[128] Nonetheless, the Soviet Union established the Democratic People's Republic of Korea (North Korea) in 1948, while the United States established the Republic of Korea (South Korea) that same year.[129] Hoping to avoid a long-term military commitment in the region, Truman withdrew U.S. soldiers from the Korean Peninsula in 1949. The Soviet Union also withdrew their soldiers from Korea in 1949, but continued to supply North Korea with military aid.[130]

On June 25, 1950, Kim Il-sung's Korean People's Army invaded South Korea, starting the Korean War. In the early weeks of the war, the North Koreans easily pushed back their southern counterparts.[131] The Soviet Union was not directly involved, though Kim did win Stalin's approval before launching the invasion.[132] Truman, meanwhile, did not view Korea itself as a vital region in the Cold War, but he believed that allowing a Western-aligned country to fall would embolden Communists around the world and damage his own standing at home.[133] The top officials of the Truman administration were heavily influenced by a desire to not repeat the "appeasement" of the 1930s; Truman stated to an aide, "there's no telling what they'll do, if we don't put up a fight right now."[134] Truman turned to the United Nations to condemn the invasion. With the Soviet Union boycotting the United Nations Security Council due to the UN's refusal to recognize the People's Republic of China, Truman won approval of Resolution 84. The resolution denounced North Korea's actions and empowered other nations to defend South Korea.[133]

North Korean forces experienced early successes, capturing the city of Seoul on June 28. Fearing the fall of the entire peninsula, General Douglas MacArthur, commander of U.S. forces in Asia, won Truman's approval to land U.S. troops on the peninsula. Rather than asking Congress for a declaration of war, Truman argued that the UN Resolution provided the presidency the constitutional power to deploy soldiers as a "police action" under the aegis of the UN.[133] The intervention in Korea was widely popular in the United States at the time, and Truman's July 1950 request for $10 billion was approved almost unanimously.[135] By August 1950, U.S. troops pouring into South Korea, along with American air strikes, stabilized the front around the Pusan Perimeter.[136] Responding to criticism over unreadiness, Truman fired Secretary of Defense Louis Johnson and replaced him with the George Marshall. With UN approval, Truman decided on a "rollback" policy—conquest of North Korea.[137] UN forces launched a counterattack, scoring a stunning surprise victory with an amphibious landing at the Battle of Inchon that trapped most of the invaders. UN forces marched north, toward the Yalu River boundary with China, with the goal of reuniting Korea under UN auspices.[138]

Territory often changed hands early in the war, until the front stabilized.
 • North Korean, Chinese, and Soviet forces
 • South Korean, U.S., Commonwealth, and United Nations forces

As the UN forces approached the Yalu River, the CIA and General MacArthur both expected that the Chinese would remain out of the war. Defying those predictions, Chinese forces crossed the Yalu River in November 1950 and forced the overstretched UN soldiers to retreat.[139] Fearing that the escalation of the war could spark a global conflict with the Soviet Union, Truman refused MacArthur's request to bomb Chinese supply bases north of the Yalu River.[140] UN forces were pushed below the 38th parallel before the end of 1950, but, under the command of General Matthew Ridgway, the UN launched a counterattack that pushed Chinese forces back up to the 38th parallel.[141]

MacArthur made several public demands for an escalation of the war, leading to a break with Truman in late 1950 and early 1951.[142] On April 5, House Minority Leader Joseph Martin made public a letter from MacArthur that strongly criticized Truman's handling of the Korean War and called for an expansion of the conflict against China.[143] Truman believed that MacArthur's recommendations were wrong, but more importantly, he believed that MacArthur had overstepped his bounds in trying to make foreign and military policy, potentially endangering the civilian control of the military. After consulting with the Joint Chiefs of Staff and members of Congress, Truman decided to relieve MacArthur of his command.[144] The dismissal of General Douglas MacArthur ignited a firestorm of outrage against Truman and support for MacArthur. Fierce criticism from virtually all quarters accused Truman of refusing to shoulder the blame for a war gone sour and blaming his generals instead. Others, including Eleanor Roosevelt, supported and applauded Truman's decision. MacArthur meanwhile returned to the U.S. to a hero's welcome, and addressed a joint session of Congress.[145] In part due to the dismissal of MacArthur, Truman's approval mark in February 1952 stood at 22% according to Gallup polls, which was, until George W. Bush in 2008, the all-time lowest approval mark for an active American president.[146] Though the public generally favored MacArthur over Truman immediately after MacArthur's dismissal, congressional hearings and newspaper editorials helped turn public opinion against MacArthur's advocacy for escalation.[147]

The war remained a frustrating stalemate for two years.[148] UN and Chinese forces fought inconclusive conflicts like the Battle of Heartbreak Ridge and the Battle of Pork Chop Hill, but neither side was able to advance far past the 38th parallel.[149] Throughout late 1951, Truman sought a cease fire, but disputes over prisoner exchanges led to the collapse of negotiations.[148] Of the 116,000 Chinese and Korean prisoners-of-war held by the United States, only 83,000 were willing to return to their home countries, and Truman was unwilling to forcibly return the prisoners.[150] The Korean War ended with an armistice in 1953 after Truman left office, dividing North Korea and South Korea along a border close to the 38th parallel.[151] Over 30,000 Americans and approximately 3 million Koreans died in the conflict.[152] The United States maintained a permanent military presence in South Korea after the war.[153]