In 1944 the Imperal Japanese Navy controlled one of the largest striking forces available to the Axis. When a census was taken of the aircraft on hand for operations on April 1, it was found that the IJN had 1,854 fighters, 930 bombers and 1,104 assorted other support aircraft. Qualitatively, many of these aircraft were superior to those produced months earlier. Starting in late 1943, the Zero Type 52 was sent to the navy in large numbers. This updated model of Japan's most famous fighter, considered its most effective variation, had been re-engineered to meet the American navy's F-6F Hellcat and F-4U Corsair carrier-based fighters. In shipping terms, the Japanese navy still retained a large fleet with an impressive mix of ships. Admiral Ozawa, who commanded the Mobile Fleet when the Battle of the Philippine Sea commenced, had nine different aircraft carriers which could launch a combined 473 aircraft. As well as the carriers, this striking force had the two largest battleships in the world (Yamato and Musashi), four other battleships, eleven excellent heavy cruisers and thirty destroyers.

The number one priority for this force of aircraft and ships was the defense of the Mariana Islands, most famously Saipan, Tinian and Guam. By way of comparison, the Japanese navy had access to many times more aircraft than the Luftwaffe had assigned to the defense of Army Group Center in the summer of 1944. The Marianas were the linchpin of Japan's defensive perimeter and had been the focus of Japanese planning for months. The Japanese navy realized that their striking force would still be smaller than the approaching American fleet possessing seven fleet aircraft carriers and eight light carriers which could launch a combined 900 aircraft. To counterbalance this inferiority, the Japanese stationed an additional 540 land-based aircraft within range of the Marianas.