page_title: Role of the United States in the Vietnam War
section_title: Operation Menu and the Cambodian campaign, 1969–70
hierarchical_section_title: Role of the United States in the Vietnam War / Vietnamization, 1969–73 / Operation Menu and the Cambodian campaign, 1969–70
caption_attribution_description: President Nixon points out the NVA sanctuaries along the Cambodian border in his speech to the American people announcing the Cambodian incursion.
context_page_description: The role of the United States in the Vietnam War began after World War II and escalated into full commitment during the Vietnam War from 1955 to 1973. The U.S. involvement in South Vietnam stemmed from a combination of factors: France's long colonial history in French Indochina, the US War with Japan in the Pacific, and both Joseph Stalin and Mao Zedong's pledge in 1950 to support Ho Chi Minh and the Viet Minh's guerrilla forces. Related to this, Roosevelt was adamantly against providing any aid to France that would in any way prop up France's struggle to maintain its pre WWII colonial empire. However, Stalin and Mao's offering their support to the Viet Minh in 1950, changed the battlefield dynamic and geopolitical character of the struggle to one of a global conflict against Maoist and Stalinist expansionism. It was at the time, in September 1950, that French forces began to be moderately backed by America. Beginning with $10M USD worth of military supplies, President Harry S.
context_section_description: By 1969 the policy of non-alignment and neutrality had worn thin for Prince Sihanouk, ruler of Cambodia. Pressures from the right in Cambodia caused the prince to begin a shift away from the pro-left position he had assumed in 1965–1966. He began to make overtures for normalized relations with the U.S. and created a Government of National Salvation with the assistance of the pro-American General Lon Nol. Seeing a shift in the prince's position, President Nixon ordered the launching of a top-secret bombing campaign, targeted at the PAVN/NLF Base Areas and sanctuaries along Cambodia's eastern border.
  On March 18, 1970, Sihanouk, who was out of the country on a state visit, was deposed by a vote of the National Assembly and replaced by General Lon Nol. Cambodia's ports were immediately closed to North Vietnamese military supplies, and the government demanded that PAVN/NLF forces be removed from the border areas within 72 hours. On March 29, 1970, the Vietnamese had taken matters into their own hands and launched an offensive against the Cambodian army. A force of North Vietnamese quickly overran large parts of eastern Cambodia reaching to within 15 miles (24 km) of Phnom Penh allowing their allies, the Chinese-supported Khmer Rouge to extend their power. Nixon ordered a military incursion into Cambodia by U.S. and ARVN troops in order to both destroy PAVN/NLF sanctuaries bordering South Vietnam and to buy time for the U.S. withdrawal. During the Cambodian Campaign, U.S. and ARVN forces discovered and removed or destroyed a huge logistical and intelligence haul in Cambodia.
  The incursion also sparked large-scale demonstrations on and closures of American college campuses. The expansion of the conflict into Cambodia was seen as an expansion of the conflict into yet another country, nullifying Nixon's promises of de-escalating the war. During the ensuing protests, four students were killed and a score were wounded by Ohio National Guardsmen during a demonstration at Kent State University. Two other students were killed at Jackson State University in Mississippi. In an effort to lessen opposition to the U.S. commitment, Nixon announced on October 12 that the U.S. would withdraw 40,000 more troops from Vietnam before Christmas.
  Following the coup, Sihanouk arrived in Beijing, where he established and headed a government in exile, throwing his substantial personal support behind the Khmer Rouge, the North Vietnamese, and the Laotian Pathet Lao.
caption: President Nixon explains the expansion of the war into Cambodia.
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