Bush ran for president in 1980, but was defeated in the Republican presidential primaries by Ronald Reagan. He was then elected vice president in 1980 and 1984 as Reagan's running mate. Bush lost the 1992 presidential election to Democrat Bill Clinton following an economic recession and the decreased emphasis of foreign policy in a post–Cold War political climate. On December 7, 1941, Japan attacked the American naval base of Pearl Harbor, marking the start of U.S. participation in World War II. On his 18th birthday, immediately after graduating from Phillips Academy, he enlisted in the United States Navy as a naval aviator. After a period of training, he was commissioned as an ensign in the Naval Reserve at Naval Air Station Corpus Christi on June 9, 1943, becoming one of the youngest aviators in the Navy.