"Philippine Sea" arrived in Korean waters on 1 August, and became flagship of Task Force 77 on 5 August. She immediately began launching air strikes against strategic targets, as the Battle of Pusan Perimeter began and United Nations and United States Army forces fought a defensive battle against the North Korean Korean People's Army. Her first strikes were against Iri, Mokpo, and Kunsan. The strikes were at first planned to target North Korean lines of communication but the intensity of the battle at Pusan Perimeter forced the carrier to fly primarily close air support missions for troops on the front lines. They also hit targets of opportunity, such as North Korean boats, bridges and dams spotted during missions. As many as 140 sorties a day were launched from the carrier. Except for brief rests to re-arm, refuel, or repair, "Philippine Sea" was in action continuously. She was put in a rotation of continuous action with "Valley Forge" to assure at least one was launching aircraft at all times. Following the beginning of The Great Naktong Offensive on 31 August, the two carriers launched 263 sorties to prevent the North Koreans from overrunning Pusan Perimeter. The ship sent sorties to defend Masan during the Battle of Masan, in spite of being from the area. The ship steamed to the southern tip of the Peninsula at on 1 September to support the Masan area more easily during the North Korean attacks.