Before World War II, the Philippines was an independent country. The encroachment of the United States on the Philippines is definitely not allowed by international morality, and it is difficult to be recognized by all countries in the world. During World War II, the United States, as a party of the "just national alliance", could not be stupid enough to become an aggressor and occupy the Philippines.
The situation in Saipan is different, and its ownership has always been complicated. The island was discovered and occupied by the Spanish during Magellan's voyage and then sold to Germany. After World War I, Germany was defeated and forced to cede the Northern Mariana Islands (including Saipan) to Japan. During World War II, in June of 1944 and 15, the US military began to attack Saipan, which was called the Battle of Saipan in history. The United States defeated Japan and captured Saipan.
After World War II, the United Nations allocated the island to the United States Government together with Micronesia, Palau and Marshall Islands for a period of 40 years (1945- 1985), and the United States was responsible for the national defense and foreign affairs of the Trust Territory. After the end of the trusteeship period, Micronesia, Palau and Marshall Islands respectively established republics, while the Northern Mariana Islands decided not to seek independence in the 1970s, but sought to become a dependency of the United States. 1975 reached an agreement with the United States to form a federation and become a political alliance of the United States. 1986 1 1 month, which became American territory by referendum.