Stalin, after talks with Kim Il-sung, accepted and supported the plan to reunify Korea by force, but he was never willing to shoulder responsibility for it. After agreeing with Kim, Stalin suggested that his Korean friends consult with Mao Zedong more often because Mao had a profound understanding of oriental questions.[13] Shtykov reminded Kim Il-sung twice to seek Mao Zedong’s opinions on reunifying Korea by force. Kim then asked Yu Chu-yon, Korea’s ambassador to China, to tell Mao Zedong that he wanted to visit China to discuss the reunification of Korea, but gave no details. Mao Zedong replied that he welcomed Kim’s visit, and that if Kim already had a specific plan for the reunification of Korea, the visit should be secret; if he did not have a specific plan, then it would be best for him to make an official visit. Mao also reminded the Korean ambassador that at present, Korea should be making military preparations in case of war.[14] Mao’s response suggests that he understood Kim Il-sung’s basic intent but had no idea of his specific plans or of the progress in talks between Kim and Stalin.
Kim Il-sung indeed paid a secret visit to Beijing in May 1950, though scholars differ in their opinions of the visit. Some maintain that after Kim went to the Soviet Union, he did not visit China at all.[15] Others say that he did visit in April or between April 7 and 26, on his way home from his Soviet tour.[16] But the recollections of Shi Zhe and recently revealed Soviet archival material show that Kim did pay a secret visit to Beijing after his Soviet tour, on May 13-16, 1950.[17]
Kim Il-sung and Park Hon-yang held talks with Mao Zedong on the very evening of their arrival in Beijing. The Korean leader first briefed Mao on the result of his discussion with Stalin, informing him of Stalin’s approval. Changes in the international situation made it possible to reunify Korea, he said, but the final decision rested with China. Mao Zedong politely expressed his opinion, saying that your Lee Sang-jo had talked with me about this question several times and each time I had told him that you could not do that now. Kim Il-sung repeatedly explained that the Soviet Union had made many preparations for us and that Stalin had agreed with his plan. We only want China to agree, he continued, we do not want any help. Mao responded that that was an important question, and that he needed to ask the Soviet ambassador to verify with Stalin what Kim had said. With that, Mao ended the talk and made an urgent appointment with the Soviet ambassador to China, and asked the latter to telegram Stalin to verify Kim’s statements.[18]
In the evening of May 14, the Soviet ambassador came to see Mao Zedong with Stalin’s telegram confirming Kim’s statements. Volkogonov included this telegram in his paper: “In a conversation with the Korean comrades, Filippov expressed the opinion that owing to the changed international situation they agree with Korea’s proposal toward reunification. With regard to this, it was stipulated that the question must be decided finally by the Chinese and Korean comrades together, and in case of disagreement by the Chinese comrades, the resolution of the of question must be put off until there is a new discussion. The Korean comrades can relay to you the details of the conversation.”[19] The tone appeared soft but was actually hard. On the surface, Stalin was asking for China’s opinion, but in fact he shifted responsibility onto China and forced Mao Zedong to make his position known. If China did not agree, reunification would be delayed; and if China agreed, the ‘final decision’ would be made by China and Korea. It seems that Mao had to agree. He told the Soviet ambassador he had taken note of the situation on the Korean Peninsula and fully agreed with the estimation of the Korean comrades that U.S. forces were gradually withdrawing and great changes had taken place. However, he maintained it was still necessary for China and Korea to rapidly sign a treaty of friendship, alliance and mutual assistance like the one signed by China and the Soviet Union.[20] In Mao Zedong’s opinion, if North Korea needed China’s direct assistance, diplomatic and political preparations were necessary. However, the fully confident Kim Il-sung needed only Mao’s nod as approval of his plan, not China’s assistance.
On May 15, Mao Zedong met again with Kim Il-sung and others. He clearly told Kim that he originally thought that Taiwan should be liberated before the settlement of the Korea question. Now that Moscow had approved the settlement of the Korea question, he agreed that Korea should be reunified first. Nonetheless, Mao once again mentioned the possibilities of the involvement of Japanese forces and intervention by the U.S. Once twenty or thirty thousand Japanese troops joined the war, he said, the whole war would be prolonged. Of course, if the U.S. became involved, China would send troops. But Kim Il-sung took no notice of the danger Mao mentioned, believing the Japanese would never become involved, the U.S. was unlikely to, and that even the entry of twenty or thirty thousand U.S. troops would not change the military situation. Stalin had told them the imperialists would not intervene, so it was unnecessary to consider it. Mao answered, I cannot decide for the imperialists. We are not their chief of staff and do not know what they are thinking about. But it is necessary to prepare for it. We are going to station three armies along the Yalujiang River. It is good if the imperialists do not intervene. If the imperialists intervene but do not cross the 38th parallel, we shall not do anything about it. If they go beyond the 38th parallel, we must cross the river to fight. Kim Il-sung thanked Mao for his offer but politely declined it. On May 16, the last day of the Mao-Kim talks, Moscow sent a telegram approving the signing of a treaty of friendship and alliance between China and Korea – not before the outbreak of war, but after the successful reunification of Korea.[21]
Based on the evidence about Kim’s secret visit to China and Mao’s understanding and approval of his plan for attacking South Korea, several observations can be made. First, Kim visited Beijing because Stalin asked him to seek China’s approval for his plan, not because he needed China’s assistance.[22] Therefore, he did not reveal his plan for attacking South Korea to China. Even later, China did not know the specific plan drawn up by Kim Il-sung and his Soviet military advisors. Shi Zhe recalls that Kim did not send a field officer to Beijing to brief China on the war situation until two days after the outbreak of war, much to Mao’s dissatisfaction. Later, Mao to Shi Zhe, “They are our next door neighbors, but they did not consult with us about the outbreak of the war. They did not come to tell us until now.”[23]