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
Imperial Japanese Navy in World War II on the American perimeter. The Japanese continued to underestimate the number of American forces on the island, assuming that were that only 2,000 marines were on the island. However, the actual number was closer to 20,000, subsequently attacks launched by the Japanese on two successive nights on September 12–14, failed. Meanwhile, the Japanese did better in the struggle for control of the waters around Guadalcanal. On September 15, the submarine sank the carrier , leaving only a single American carrier, the , active in the Pacific at the time. However, as the Japanese possessed up to six operational carriers during