A mutual security organization composed of representatives of Britain, Turkey, Iran, Pakistan, and Iraq. In 1956 the USA became an associate member. Formed as a result of the Baghdad Pact (1955), it was designed in part as a defence against the former Soviet Union and to consolidate the influence of Britain in the Arab world. Following the withdrawal of Iraq (1958), its headquarters were moved to Ankara. It became inactive after the withdrawal of Turkey, Pakistan, and Iran in 1979.