The Second Sino-Japanese War was a military conflict that was primarily waged between the Republic of China and the Empire of Japan from July 7, 1937, to September 2, 1945. The start of the war is typically considered to be the Marco Polo Bridge Incident in 1937, in which a dispute between Japanese and Chinese troops escalated into a full-scale invasion. Some sources in the modern People's Republic of China date the beginning of the war to the Japanese invasion of Manchuria in 1931. In China, it is known as the War of Resistance against Japanese Aggression.
China fought Japan with aid from the Soviet Union and the United States. After the Japanese attacks on Malaya and Pearl Harbor in 1941, the war merged with other conflicts of World War II as a major sector known as the China Burma India Theater. Some scholars consider the start of the full-scale Second Sino-Japanese War in 1937 to have been the beginning of World War II. The Second Sino-Japanese War was the largest Asian war in the 20th century.