Hainan Island Operation
The Japanese Navy, after the capture of Canton the previous year, had maintained a formidable blockade all along the coast of south, central and north China.
However, loopholes were found in the southern end of the blockade line, examples being the supply route to Chiang Kai-shek with Hongkong and Northern trench Indo-China as relay points and the direct routes though Hainan Island and Kwangchowan areas. Because of these loopholes, as well as the necessity to conduct air operations deep into the interior as far as the Kunming area, the Navy came to feel the necessity for establishing air bases on Hainan Island. The Central Authorities of the Navy advocated this move.
The Hainan Island Operation, or Kainan-tō sakusen (海南島作戦) in Japanese was part of a campaign by the Empire of Japan during the Second Sino-Japanese War to blockade the Republic of China to prevent it from communicating with the outside world and importing needed arms and materials. Control of Hainan Island also provided a base of operations for the invasion of Guangdong province and French Indochina, and also provided airbases to permit long-distance air raids at routes into China from French Indochina and Burma.