Why did the United States involve itself in the Korean War? What was the cause of the American involvement, and what political and military implications did it have both then and after? In this two-part study, we will review in Part I the beginning of the Cold War, the United States's policy of containment, and the circumstances that brought about the Korean War. Part II will examine the United States's entrance in the war and how the war influenced America's domestic politics and its current role in foreign affairs.

The "Iron Curtain"

In post-World War II Europe, the map of nation-states had changed drastically, and the traditionally dominate powers, such as Great Britain and France, had lost their influence as leaders in geopolitics. Per the Yalta Conference of 1945, Allied leaders of the United States and Great Britain allowed Soviet dictator Joseph Stalin to maintain his hold on countries he had "liberated" from Nazi Germany, on condition that Stalin allow free elections in the regions he had taken and also provide military aid to the United States for their efforts against Japan. On the first account, Stalin went back on his word, nonetheless maintaining a firm grip on Eastern European countries of Romania, Poland, Hungary, Czechoslovakia, Albania, Bulgaria, and the eastern portion of Germany.

As Stalin desired to expand his territory, called the Communist Bloc, it was clear to the Allies that the Soviets were a threat to the "free world" of Western Europe and the United States. In particular, he was not pleased with the division of Germany, in which he controlled the East, the Allies held the West, and Berlin was divided between America, Britain, France, and the Soviets. When the Allies unified all of their territory to create the nation of West Germany, Stalin began growing more suspicious of the Allies' intentions, especially when they unified their portions of Berlin, a region he wanted complete control over. In 1946, Sir Winston Churchill lamented that an "iron curtain [had] descended across the continent," and behind that curtain to the East lay all the countries within the "Soviet sphere." Churchill worried that Western Europe, devastated by the loss of manpower, finances, and infrastructure during the Second World War, would not be able to respond adequately if Stalin expanded the Soviet sphere. As the Soviets were already supporting Communist insurgencies in other nations, the Europeans were forced to turn to the strongest nation in the free world: the United States.

The Truman Doctrine, 1947

Initially, the United States was reluctant to involve itself in foreign affairs. Historically, Americans were recluses: after any war, even the First World War, when the fighting was over, troops were brought home, and the military was reduced. The United States government was nonetheless aware of the Soviet threat, hence, despite little support from the public, President Harry Truman issued the Truman Doctrine in 1947.

In response to British calls for aid in protecting the Greek government from Soviet-backed communist insurgents, the Truman Doctrine stated that the United States would support any anticommunist activity in nations not already part of the Communist Bloc, a policy known as containment. Truman's justification for foreign involvement was that if the Soviets remained unchecked, the would expand until they had taken Western Europe, becoming a direct threat to the United States. With the advent of the Truman Doctrine, American leadership in the Free World was solidified.

Strife in China and Korea, 1945-1950

The United States pursued fought in Greece until it was finally achieved achieved victory, which it did in 1949. Tensions over Berlin resulted in Stalin blockading the portion held by the West in 1948, cutting off all supplies. The United States, Great Britain, and France responded by sending their air forces to drop supplies to the Berliners, until Stalin finally relieved pressure in 1949. But the Cold War had yet to see two of its greatest early conflicts: the Chinese Civil War and the Korean War.

The Korean War began in the midst of heightened tensions between the United States and the Soviet Union. The Soviets had been aiding Communist insurgencies in other nations, notably China. After the Japanese from Chinese territory they had gain during World War II, the shaky Nationalist government of China fought against Communist insurgents backed by the Stalin. After the Chinese Communists won and established the People's Republic of China in 1949, Stalin turned to a conflict brewing in Korea.

Korea, like China, had been subject to Japanese invasion during World War II, by 1945, the United States accepted the surrender of Japan's Korean territory south of the 38th parallel, and the Soviets held the north. In a joint commission, the Americans and the Soviets attempted to raise up plans for a five-year move toward the unification of the Korean Peninsula. Disagreements over whether or not to allow Korean representatives in on the proceedings spelled failure for the joint commission, and both sides went to maintain their respective regions.

North Koreans led by Kim Il-sung were keen on the unification of Korea under a Communist regime, and, despite the South Koreans purging Communists in their own territory. In 1949, Il-sung turned to Stalin, requesting help for a full-scale invasion of the South. Stalin refused. At the time, the Soviets were providing war materiel to Chinese Communists during their Civil War, and North Korea lacked sufficient manpower, having sent tens of thousands of troops to the Chinese to beat the Nationalists. In addition, the United States still maintained a military presence in the South, and Stalin did not want to risk entanglement war with America.

Circumstances changed when the Chinese Communists beat the Nationalists. Stalin could stop supporting the Chinese and since the North Korean troops were no longer needed, and over the course of the Korean War, the Chinese sent back over 50,000 of them. By June 1949, the United States had evacuated its forces from the South, having helped the South Koreans establish a government and a 98,000 man "police force" with small arms, lacking in heavy military equipment. With the promise of the new Chinese government's military support when the North Koreans invaded the South, Stalin pledged aid in the form of arms and aircraft.

Korean War Begins, 1950

Equipped with the necessary tools, Kim Il-sung began his invasion of Korea in June 1950. The international community was shocked, and the United States, having brought back its forces in 1949, lacked the ability to respond. Crossing the 38th parallel, North Korean forces beat the ill-equipped South Koreans; on June 28, the South Korean government evacuated its capital, Seoul, and the North Koreans took it over. By August 1950, the North Koreans had taken most of the South.

Truman would appeal to the United Nations Security Council that same year, asking for international cooperation and military aid in pushing back the North Korean Communists, however, the forces supplied by the United States and the United Nations were unable to fight effectively, due especially to the defense budget cuts the Truman administration had passed during the aftermath of World War II. It would not be until November 1950 that the United States would be able to supply enough troops and equipment for the war effort. The Korean War had begun, and the Free World was unprepared.

Thanks for reading, stay tuned for Part II.