Japanese air attacks on the Mariana Islands 27 in preparation for operations against Japan itself. The USAAF bases in the Mariana Islands were within range of a number of Japanese air bases in the Pacific. These included Wake Island to the east, Truk and the Gilbert and Marshall Islands to the southeast, Woleai to the south and Yap to the southwest. To the north the Japanese had air bases in the Nampo Shoto chain of islands and Bonin Islands, which included three airstrips on Iwo Jima. Several of the minor islands in the Mariana chain also remained in Japanese hands, and there were airfields on Rota and
Japanese colonial empire provided convenient provisioning locations for ships. During the 1930s, the Imperial Japanese Navy began construction of airfields, fortifications, ports, and other military projects on the South Pacific Mandate islands, viewing them as "unsinkable aircraft carriers" with a critical role to play in the defense of the Japanese home islands against potential invasion by the United States. The islands became important staging grounds for Japanese air and naval offensives during the Pacific War, but were lost to American military action between 1943 and 1945. The League of Nations mandate was formally revoked by the United Nations on July 18, 1947 pusuant