As a U.S. Congressman in 1951, Kennedy became fascinated with Vietnam after visiting the area as part of a big fact-finding mission to Asia and the Middle East, even stressing in a subsequent radio address that he strongly favored “check the southern drive of communism.” As a U.S. Senator in 1956, Kennedy publicly advocated for greater U.S. involvement in Vietnam. When briefing Kennedy, Eisenhower emphasized that the communist threat in Southeast Asia required priority; Eisenhower considered Laos to be "the cork in the bottle" regarding the regional threat. In March 1961, Kennedy voiced a change in policy from supporting a "free" Laos to a "neutral" Laos, indicating privately that Vietnam, and not Laos, should be deemed America's tripwire for communism's spread in the area. In May, he dispatched Lyndon Johnson to meet with South Vietnamese President Ngo Dinh Diem. Johnson assured Diem more aid to mold a fighting force that could resist the communists. Kennedy announced a change of policy from support to partnership with Diem to defeat of communism in South Vietnam.