A. Philippines gets invaded by China, and takes over, say 7% of the islands in the Philippines. B. US finds out, gets real concerned because of Chinese aggression, sends more troops to Japan and South Korea, but waits, hoping not to go to war with a growing superpower, hoping for some diplomatic resolution. read more
WW2 is history, no point in thinking in terms of invasion. There is no reason for the Chinese to invade the Philippines, and if they wanted to neutralize the Philippine Navy and Air Force they could do it in minutes. read more