Operation I-Go was an aerial counter-offensive launched by Imperial Japanese forces against Allied forces during the Solomon Islands and New Guinea campaigns in the Pacific Theater of World War II. Taking place from 1–16 April 1943, Japanese aircraft—primarily from Imperial Japanese Navy units under the command of Admirals Isoroku Yamamoto and Jinichi Kusaka—attacked Allied ships, aircraft, and land installations in the southeast Solomon Islands and New Guinea. The goal of the operation was to halt the Allied offensives to give Japan time to prepare a new set of defenses in response to recent defeats in the Guadalcanal campaign and in New Guinea at Buna–Gona, Wau, and the Bismarck Sea.

The New Guinea campaign of the Pacific War lasted from January 1942 until the end of the war in August 1945. During the initial phase in early 1942, the Empire of Japan invaded the Territory of New Guinea on 23 January and Territory of Papua on 21 July and overran western New Guinea beginning on 29 March. During the second phase, lasting from late 1942 until the Japanese surrender, the Allies—consisting primarily of Australian forces—cleared the Japanese first from Papua, then New Guinea, and finally from the Dutch colony.