In the 1930s and '40s, the main military adversary of China was the Empire of Japan. In the context of a weak domestic industrial base, China aircraft in this period was mainly acquired in other countries. The main supplier of aircraft to the Chinese Air Force were the United States, and after the outbreak of war with Japan, a large number of aircraft arrived from the Soviet Union 1937-1940. World of Warplanes features fighting vehicles used in the Second Sino-Japanese War and the Civil War in China.