Some A5Ms remained in service at the end of 1941 when the United States entered World War II in the Pacific. US intelligence sources believed the A5M still served as Japan's primary Navy fighter, when in fact the A6M 'Zero' had replaced it on first-line aircraft carriers and with the Tainan Kōkūtai in Taiwan. Other Japanese carriers and Kōkūtai (air groups) continued to use the A5M until production of the Zero caught up with demand. On 1 February 1942, the US carrier "USS Enterprise" launched air-strikes at Japanese air & naval bases on Roi and Kwajalein Atolls in the Gilbert Islands. During these actions, Mitsubishi A5Ms shot down three Douglas SBD dive-bombers, including the aircraft of Lt-Cdr Halstead Hopping, CO of VS-6 Squadron. The last combat actions with the A5M as a fighter took place at the Battle of the Coral Sea on 7 May 1942, when two A5Ms and four A6Ms of the Japanese carrier fought against US aircraft that sank their carrier.