The Vietnam War (also known by other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vietnam and South Vietnam. The north was supported by the Soviet Union, China, and other communist states, while the south was supported by the United States and other anti-communist allies. The war is widely considered to be a Cold War-era proxy war. It lasted almost 20 years, with direct U.S. involvement ending in 1973. The conflict also spilled over into neighboring states, exacerbating the Laotian Civil War and the Cambodian Civil War, which ended with these two countries becoming communist states by 1975. After the French withdrawal from Indochina in 1954 – following defeat of the French Union in the First Indochina War – Vietnam was divided into North and South Vietnam: the communist-led Viet Minh took control of North Vietnam, and the U.S. assumed financial and military support for the South Vietnamese state led by an anti-communist government. The Viet Cong (VC), a South Vietnamese common front under the direction of the north, initiated a guerrilla war in the south. The People's Army of Vietnam (PAVN), also known as the North Vietnamese Army (NVA), engaged in more conventional warfare with U.S. and South Vietnamese forces (ARVN). North Vietnam invaded Laos in 1958, establishing the Ho Chi Minh Trail to supply and reinforce the VC. By 1963, the north had sent 40,000 soldiers to fight in the south. U.S. involvement increased under President John F. Kennedy, from just under a thousand military advisors in 1959 to 23,000 by 1964. Following the Gulf of Tonkin incident in August 1964, the U.S. Congress passed a resolution that gave President Lyndon B. Johnson broad authority to increase U.S. military presence in Vietnam, without a formal declaration of war. Johnson ordered the deployment of combat units for the first time, and dramatically increased the number of American troops to 184,000. U.S. and South Vietnamese forces relied on air superiority and overwhelming firepower to conduct search and destroy operations, involving ground forces, artillery, and airstrikes. The U.S. also conducted a large-scale strategic bombing campaign against North Vietnam, and continued significantly building up its forces, despite little progress being made. In 1968, North Vietnamese forces launched the Tet Offensive; though it was a