By 1962, Attorney General Robert Kennedy was President John Kennedy's closest adviser, even in foreign affairs. This was most evident during the Cuban Missile Crisis of October 1962. When reconnaissance flights detected Soviet missiles in Cuba, President Kennedy and his advisers agreed that this should not be allowed, but disagreed on how to get Nikita Khrushchev to remove them. Some advocated an air strike; Robert Kennedy was among the most vocal against such an attack, calling it "Pearl Harbor in reverse." He convinced his brother to establish a naval blockade to turn back Soviet ships carrying missiles. After a tense week long showdown bringing the U.S. and Soviet Union the closest they would come to nuclear conflict, Khrushchev agreed to call back his ships in return for a U.S. promise not to invade Cuba.