The Gulf of Tonkin Incident occurred during the first year of the Johnson administration. While US President John F. Kennedy had originally supported the policy of sending military advisers to Diem, he had begun to alter his thinking due to what he perceived to be the ineptitude of the Saigon government and its inability and unwillingness to make needed reforms (which led to a U.S.-supported coup which resulted in the death of Diem). Shortly before Kennedy was assassinated in November 1963, he had begun a limited recall of U.S. forces. Johnson's views were likewise complex, but he had supported military escalation as a means of challenging what was perceived to be the Soviet Union's expansionist policies. The Cold War policy of containment was to be applied to prevent the fall of Southeast Asia to communism under the precepts of the domino theory. After Kennedy's assassination, Johnson ordered in more U.S. forces to support the Saigon government, beginning a protracted United States presence in Southeast Asia.