This time, Stalin seemed convinced.  After Kim’s secret visit, Stalin finally approved Kim’s military plan. Yu Song-chol, minister for Military Operations of the Korean People’s Army, took part in the war preparations.  In the early 1990s, he recalled that Soviet military advisors planned for an operation that would take only four days, since they assumed that the war would be over once the People’s Army took Seoul.[66] Soviet leaders clearly assumed that the U.S. would have no time to intervene once the Korean War began.

       Third, Stalin fully evaluated the potential effects of a possible U.S. intervention.  His general strategy was to involve China. In discussions with Kim Il Sung, Stalin repeatedly stressed the necessity of asking Mao’s permission for any attack on South Korea. M. S. Kapitsa, officer in charge of affairs of the People's Democratic Republic of Korea, remembers that in their final conversation in April 1950, Stalin urged Kim to consult Mao again.  He warned: “If you should get kicked in the teeth, I shall not lift a finger. You have to ask Mao for all the help.”[67] Stalin cabled Mao on 14 May and told him that Moscow had agreed to Kim’s proposal for military action, but he insisted that the final decision rested with the China and North Korea.  If the Chinese were reluctant, the matter had to be postponed.[EAM3] [68]  It was obvious that Stalin wished to force China to shoulder the responsibility of aiding North Korea if the United States intervened in the conflict.

       In essence, Stalin faced two requests in 1950.  Kim Il Sung needed Moscow’s permission and assistance for his attack on South Korea.  Mao hoped for Soviet military aid in his campaign to “liberate” Taiwan.  For Stalin, the decision was not difficult.  A unified Korea would be under Soviet control.  A China victorious in Taiwan would be a potential rival for Soviet influence in the Far East.  While Kim Il Sung needed only Soviet military assistance, Mao needed direct air and naval support for the Taiwan campaign, particularly after the People's Liberation Army's (PLA) failed invasion of Jinmen Island in October 1949.[69] Since Stalin wished both to unify the Korean peninsula and to subject China to Soviet influence, the Korean conflict seemed a perfect means of achieving both ends.  The outbreak of the Korean War would prevent China from attacking Taiwan, and, at the same time, it would place China’s military at the service of Soviet strategy.  Stalin knew that Mao was reluctant to intervene in Korea before the CCP had consolidated its power and achieved China’s unification. But Stalin had to ensure that China would back the North Korean Communists before he approved Kim’s invasion plans.

Mao’s reaction to Soviet and North Korean plans is now better understood because of newly available evidence.  Four questions regarding Mao’s strategic thinking can now be provisionally answered. [EAM4] 

First, did China specifically endorse Kim Il Sung’s military action against the South?  As early as May 1949, Kim Il Sung sent Kim Il,  the director of the Political Department of the People’s Army, on a secret visit to Beijing.  Kim Il met Zhu De and Zhou Enlai four times and met Mao on