The first event that is usually linked to the later Pacific conflict was the Mukden Incident of 18 September 1931, during which the Japanese military staged the bombing of the South Manchuria Railway and pinned the blame on Chinese dissidents. Japan then used this as pretext to invade northeastern China the next day and turn the region of Manchuria into the Japanese puppet state of Manchukuo. After the League of Nations commissioned the 1932 Lytton Report, which exposed the Mukden Incident as a Japanese ruse, Japan was left internationally isolated, withdrawing from the League of Nations in March 1933. In 1934 Manchukuo became a constitutional monarchy and the former Chinese Emperor Pu Yi was placed on the throne, despite the real power being held by Japan.