The Second Sino-Japanese War merged into which war?

The Second Sino-Japanese War was a military conflict fought primarily between the Republic of China and the Empire of Japan from July 7, 1937, to September 2, 1945. It began with the Marco Polo Bridge Incident in 1937 in which a dispute between Japanese and Chinese troops escalated into a battle. Some sources in the modern People's Republic of China date the beginning of the war to the Japanese invasion of Manchuria in 1931. It is known as the War of Resistance in China.

China fought Japan with aid from the Soviet Union and the United States. After the Japanese attack on 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. It accounted for the majority of civilian and military casualties in the Pacific War, with between 10 and 25 million Chinese civilians and over 4 million Chinese and Japanese military personnel dying from war-related violence, famine, and other causes.