Yes, the Japanese absolutely considered the occupation of the Philippines a necessary operation if Japan was to go south. The Imperial Japanese Army (IJA) even questioned whether operations against Malaya and the Dutch East Indies could proceed without simultaneous occupations of the Philippines, but the Imperial Japanese Navy (IJN) asserted that occupation of the Philippines were absolutely necessary to success of the southern advance. The Navy's perspective was that, if the Philippines were not occupied by the Japanese, the American forces there would be an unacceptable threat to the shipping lanes that would provide the necessary links between the newly acquired Southern Resource Area and Japan. Indeed, the Japanese need to occupy the Philippines, and the expected subsequent war against the United States that led to the decision to strike pre-emptively at Pearl Harbor, as they hoped to delay the anticipated American counterattack until after the Japanese had successfully occupied their objectives.