Central Treaty Organization (CENTO), a former mutual-defense alliance of Iran, Turkey, Pakistan, and Great Britain. The United States was an associate member. The objective of the alliance was to prevent the spread of Communism and of Soviet influence in the Middle East. In the event of aggression against any of the Middle Eastern members of the alliance, the United States was pledged to take such appropriate action as would be mutually agreed upon. The members engaged in many cooperative nonmilitary projects.

CENTO was formed in 1955 at Baghdad, Iraq, as the Middle East Treaty Organization (METO), and was commonly also referred to as the Baghdad Pact. When Iraq, one of the original members, withdrew in 1959 the alliance was reorganized under the new name. With the withdrawal of Pakistan and Iran in 1979, CENTO collapsed.