the Japanese imperial army during the 1920s and 1930s, including the Battle of Fengwudong in June 1920, the Battle of Qingshanli in October 1920, and Yoon Bong-Gil's assassination of Japanese officers in Shanghai in April 1932. Korean independence activists often fled to China, Russia and the United States, where they fomented plans to restore Korean sovereignty. Several notable examples include the inclusion of Koreans into the Republic of China's Whampoa Military Academy, where many Koreans trained in military tactics and strategy. When Imperial Japan invaded China in 1937, sparking the Second Sino-Japanese War, the Provisional Government relocated to Chongqing and created the Korean Liberation Army to fight alongside Chinese forces against Japan.Originally, the Republic of China placed the Korean Liberation Army under the supreme authority of the commander-in-chief of the Chinese Army. The regulation was repealed in 1944, after the Provisional Government had achieved had improved its financial standing and achieved greater importance in the eyes of the Chinese government. The hundreds-strong KLA engaged in guerrilla warfare actions against the Japanese throughout the Asian theater of war until Japanese surrender in 1945. Japanese control of Korea ended on September 9, 1945, when the Japanese Governor-General of Korea signed the surrender document of the United States in Seoul. Post World War II At the end of World War II, Korea regained its independence after 35 years of imperialist Japanese rule. Per the Yalta Conference agreements, Soviet forces accepted surrender of Japanese forces in northern Korea above the 38th parallel, and U.S. forces south of that line. Korea was then divided into Soviet (North Korean) and U.S. (South Korean) spheres. South Korea refused diplomatic and trade relations with Japan, using tensions with Japan to rally support for the South Korean government. The early ROK (Republic of Korea; South Korea) government derived its legitimacy from its opposition to Japan and North Korea, portraying South Korea as under threat from the North and South. The diplomatic relationship between Japan and South Korea was established in 1965, when the Treaty on Basic Relations was signed; Japan subsequently recognized the Republic of Korea (the official name of South Korea) as the only legitimate government on the Korean Peninsula. As such, North Korea does not have official diplomatic ties with Japan. 21st century Despite the ongoing historical tension between Japan-Korean that has impacted their relations they have since been able to interact with each other. In recent