The Empire of Japan's Kwantung Army invaded Manchuria on 18 September 1931, immediately following the Mukden Incident. At the war's end in February 1932, the Japanese established the puppet state of Manchukuo. Their occupation lasted until the success of the Soviet Union and Mongolia with the Manchurian Strategic Offensive Operation in mid-August 1945, towards the end of the Second World War. The South Manchuria Railway Zone and the Korean Peninsula had been under the control of the Japanese Empire since the Russo-Japanese War of 1904–1905. Japan's ongoing industrialization and militarization ensured their growing dependence on oil and metal imports from the US. The US sanctions which prevented trade with the United States (which had occupied the Philippines around the same time) resulted in Japan furthering its expansion in the territory of China and Southeast Asia. The invasion of Manchuria, or the Marco Polo Bridge Incident of 7 July 1937, are sometimes cited as alternative starting dates for World War II, in contrast with the more commonly accepted date of September 1, 1939. With the invasion having attracted great international attention, the League of Nations produced the Lytton Commission (headed by British politician Victor Bulwer-Lytton) to evaluate the situation, with the organization delivering its findings in October 1932. Its findings and recommendations that the Japanese puppet state of Manchukuo not be recognized and the return of Manchuria to Chinese sovereignty prompted the Japanese government to withdraw from the League entirely. Background A minor dispute known as the Wanpaoshan incident between Chinese and Korean farmers occurred on July 1, 1931. The issue was highly sensationalized in the Imperial Japanese and Korean press, and used for considerable propaganda effect to increase anti-Chinese sentiment in the Empire of Japan. Believing that a conflict in Manchuria would be in the best interests of Japan, and acting in the spirit of the Japanese concept of gekokujō, Kwantung Army Colonel Seishirō Itagaki and Lieutenant Colonel Kanji Ishiwara independently devised a plan to provoke Japan into invading Manchuria by setting up a false flag incident for the pretext of invasion. The operation was originally planned to be executed on 28 September, but the date was changed to September 18. When 1st Lieutenant Suemori Komoto of the Independent Garrison Unit (独立守備隊) of the 29th Infantry Regiment (which guarded the South Manchuria Railway) placed explosives near the tracks, but far enough away to do no real damage. At around 10:20