DWIGHT D. EISENHOWER TIMELINE BIOGRAPHY

    ...Troubles in the Middle East also demanded he President's attention. In 1953 the United States covertly backed anti-government forces in Iran, which overthrew a communist-backed regime and restored the pro-West Shah to power. In late 1956 tensions ran high when the Suez Canal Crisis erupted: Israel invaded the Gaza Strip and the Sinai Peninsula while British and French forces attacked Egyptian bases near the Canal because Egyptian President Nasser had nationalized the international waterway. But Eisenhower refused to back America's closest allies, certain that if the U.S. entered the conflict on the side of the European colonial powers and Israel, such intervention would destroy American prestige among Third World Nations. The result would be massive Soviet penetration of these developing nations. Lacking U.S. support, England and its friends backed off, and the crisis eased.

Nevertheless, instability in the Middle East continued, leading to the Eisenhower Doctrine in 1957, which authorized the use of U.S. forces to assist Middle East nations whose political instability would invite Soviet penetration. In 1958 the President deployed Marines to Lebanon in order to stabilize exactly that kind of situation....

http://www.eisenhower.archives.gov/ddebio.htm