When examining the outbreak and protracted course of the Sino-Japanese War, it is important to note the attitudes of neighboring countries such as the United States and the Soviet Union toward the Sino-Japanese issue, which arose as a result of Japan's aggressive continental policy, and how these attitudes influenced the outbreak of the war. Given that the Sino-Japanese War was a protracted eight-year war fought by the Chinese government with the support of the Soviet Union, the United States, and the United Kingdom, and that it was an international event that directly influenced the outbreak of the Asia-Pacific War, it is necessary to understand the diplomatic process surrounding the war, not just the decision to escalate the war within the Japanese leadership and the decision to wage a protracted global war. After the Manchurian Incident, Japan's East Asian policy included an aggressive expansion of its influence on the Chinese mainland, which was embodied in aggressive public policies such as the army-led campaign to separate Hwaseong from North Korea. In response to these Japanese public policies, the Chinese government actively sought internal and diplomatic means to resist, while the Soviet Union and the United States, both of which were paying attention to East Asian affairs, gradually shifted their policies toward supporting China in the Sino-Japanese conflict and deterring Japanese aggression. The fact that 1935 was the year when Japan's public policy became overtly aggressive, as symbolized by the separation of Hwaseong, and that Sino-Japanese relations began to trend in a friendly direction from this year shows that the attitude of neighboring countries toward the Sino-Japanese dispute had already shifted in a direction favorable to China before the outbreak of the Sino-Japanese War.
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