Those withdrawals did take place, in 1948-49, but there was no agreement on who would run the country. Instead it remained divided, with the American-supported Republic of Korea in control of the south by virtue of an election sanctioned by the United Nations, while the Soviet-supported Democratic Republic of Korea ruled the north, where elections were not held. The only thing unifying the country by then was a civil war, with each side claiming to be the legitimate government and threatening to invade the other.
Neither could do so, however, without superpower support. This the Americans denied to their South Korean allies, chiefly because the Truman administration had decided to liquidate all positions on the Asian mainland and concentrate on the defense of island strongpoints like Japan, Okinawa, and the Philippines—though not Taiwan. The South Korean president, Syngman Rhee, repeatedly sought support for his ambitions to liberate the north from officials In Washington, as well as from General Douglas MacArthur, the commander of United States occupation forces in Japan, but he never got it. One of the reasons the Americans withdrew their troops from South Korea, indeed, was their fear that the unpredictable Rhce might "march north," and thus drag them into a war they did not want.
Rhee’s North Korean counterpart, Kim Il-sung, had similar designs on the south, and for a time a similar experience with his superpower sponsor. He had repeatedly sought support in Moscow for a military campaign to unify Korea, and had been repeatedly turned down—until January, 1950, when yet another request got a more encouraging response. What made the difference, it appears, was Stalin's conviction that a "second front" was now feasible in East Asia, that it could be created by proxies, thus minimizing the risk to the U.S.S.R., and that the Americans would not respond. They had done nothing, after all, to save tire Chinese nationalists, and on January l2, 1950, Secretary of State Acheson had even announced publicly that the American "defensive perimeter" did not extend to South Korea. Stalin read the speech carefully—as well as (courtesy of British spies) the top-secret National Security Council study upon which it was based—and authorized Ills foreign minister, Molotov, to discuss it with Mao Zedong. The Soviet leader then informed Kim Il-sung that "[a]ccording to information coming from the United States, . . . [t]he prevailing mood is not to interfere." Kim in turn assured Stalin that "[t]he attack will be swift and the war will he won in three days."
Stalin's "green light" to Kim Il-sung was part of the larger strategy for seizing opportunities in East Asia that he had discussed with the Chinese: shortly after endorsing the invasion of South Korea, he also encouraged Ho Chi Minh to intensity the Viet Minh offensive against the French in Indochina. Victories in both locations would maintain the momentum generated by Mao's victory the previous year. They would compensate for the setbacks the Soviet Union had encountered in Europe, and they would counter increasingly obvious American efforts to bring Japan within its system of postwar military alliances. A particular advantage of this strategy was that it would not require direct Soviet involvement: the North Koreans and the Viet Minh would take the initiative, operating under the pretext of unifying their respective countries. And the Chinese, still eager to legitimize their revolution by winning Stalin's approval, were more than willing to provide backup support, if and when needed.
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