Most historians place the beginning of the second Sino-Japanese War on the Battle of Lugou Bridge (Marco Polo Bridge Incident) on July 7, 1937. However, Chinese historians place the starting point at the Mukden Incident of September 18, 1931. Following the Mukden Incident, the Japanese Guandong Army occupied Manchuria and established the puppet state of Manchukuo (February 1932). Japan pressured China into recognising the independence of Manchukuo. China and Japan did not formally declare war against each other until after the attack on Pearl Harbor on December 7, 1941.