Suez Crisis led to a withdrawal. U.S. President Dwight D. Eisenhower had strongly warned Britain not to invade; he threatened serious damage to the British financial system by selling the US government's pound sterling bonds. Historians conclude the crisis "signified the end of Great Britain's role as one of the world's major powers". The Suez Canal was closed from October 1956 until March 1957. Israel fulfilled some of its objectives, such as attaining freedom of navigation through the Straits of Tiran, which Egypt had blocked to Israeli shipping since 1950. As a result of the conflict, the United Nations created the UNEF
Nassau Agreement and probably would have worked for the RAF into the 1970s, as it did for the USAF. It therefore came down to Polaris, which the US did not wish to supply except as part of a Multinational Force. Macmillan was emphatic that he would commit the submarines to NATO only if they could be withdrawn in case of a national emergency. When pressed by Kennedy as to what sort of emergencies he had in mind, Macmillan mentioned the Soviet threats at the time of the Suez crisis, Iraqi aggression against Kuwait, or a threat to Singapore. The British nuclear deterrent