IV.

The War Begins: Soviet, Chinese, and U.S. Support

Throughout 1949 the Soviet Union feared the consequences that an invasion by North Korea would have on U.S.-Soviet relations. Consequently, for months Soviet leader Joseph Stalin declined to support Kim’s plans for war. In early 1950, however, Stalin appeared to give his endorsement to Kim; he also suggested that Kim seek support from Chinese leader Mao Zedong. The reasons for Stalin’s shift are still not clear but may have been related to American plans for a major Cold War military buildup. The Chinese response to Kim's entreaty is also still unknown, but it seems unlikely that the Chinese did not know of Kim's plans. Indeed, they sent many experienced Korean soldiers back to Korea from China just before the war erupted.

The United States maintained throughout 1949 and 1950 that it would not support an invasion of the North by the South. As early as 1947, however, Acheson and his advisers had come to see South Korea as important to the revival of the Japanese industrial economy, which provided goods and services to Korea. From that time on, U.S. policymakers were privately committed to extending the Truman Doctrine, which called for the containment of Communism, to South Korea. Even after U.S. combat troops left South Korea in 1948, a large military advisory group remained in the ROK, and the United States gave the republic great amounts of economic aid. When the Soviet-backed North invaded—unprovoked, in the perception of the U.S. government—Acheson and President Harry S. Truman led the United States into the war, despite objections from many U.S. military commanders who thought Korea was the wrong place to make a stand against Communism.