In July 1956, Nasser unilaterally nationalised the Suez Canal. The response of Anthony Eden, who had succeeded Churchill as Prime Minister, was to collude with France to engineer an Israeli attack on Egypt that would give Britain and France an excuse to intervene militarily and retake the canal. Eden infuriated US President Dwight D. Eisenhower, by his lack of consultation, and Eisenhower refused to back the invasion. Another of Eisenhower's concerns was the possibility of a wider war with the Soviet Union after it threatened to intervene on the Egyptian side. Eisenhower applied financial leverage by threatening to sell US reserves of the British pound and thereby precipitate a collapse of the British currency. Though the invasion force was militarily successful in its objectives, UN intervention and US pressure forced Britain into a humiliating withdrawal of its forces, and Eden resigned.