The outbreak of the Korean War in June 1950 convinced many Washington policymakers that the war in Indochina was an example of communist expansionism directed by the Soviet Union. Military advisors from the People's Republic of China (PRC) began assisting the Viet Minh in July 1950. PRC weapons, expertise, and laborers transformed the Viet Minh from a guerrilla force into a regular army. In September 1950, the United States created a Military Assistance and Advisory Group (MAAG) to screen French requests for aid, advise on strategy, and train Vietnamese soldiers. By 1954, the United States had spent US$1 billion in support of the French military effort, shouldering 80 percent of the cost of the war. During the Battle of Dien Bien Phu, U.S. carriers sailed to the Gulf of Tonkin and the U.S. conducted reconnaissance flights. There were also talks between the French and Americans in which the possible use of three tactical nuclear weapons was considered, though reports of how seriously this was considered and by whom are vague and contradictory. According to U.S. vice president Richard Nixon, the plan involved the Joint Chiefs of Staff drawing up plans to use three small tactical nuclear weapons in support of the French. Nixon, a so-called "hawk" on Vietnam, suggested that the United States might have to "put American boys in". U.S. president Dwight D. Eisenhower made American participation contingent on British support, but the British were opposed. Eisenhower decided against U.S. military intervention, being wary of getting the United States involved in a land war in Asia. Throughout the conflict, U.S. intelligence estimates remained skeptical of French chances of success. On 7 May 1954, the French garrison at Dien Bien Phu surrendered. The defeat marked the end of French military involvement in Indochina. At the Geneva Conference, the French negotiated a ceasefire agreement with the Viet Minh, and independence was granted to Cambodia, Laos, and Vietnam. At the 1954 Geneva peace conference, Vietnam was temporarily partitioned at the 17th parallel. Ho Chi Minh had wished to continue the war in the south, but was restrained by his Chinese allies who convinced him that he could win control by electoral means. Under the terms of the Geneva Accords, civilians were to be given the opportunity to move freely between the two provisional states for a 300-day period. Elections throughout the country were to be held in 1956 to establish a unified government. Around one million northerners, mainly minority Catholics, fled south, fearing persecution by the communists.