Cambodia’s ties to Vietnam can be traced back to 1953 when Cambodia was granted independence. By 1954, The Geneva Accords divided Vietnam at the 17th parallel and also recognized Cambodia as an independent state. Soon after, the US gave Cambodia over $85 million to train their own army; however, by 1958 Cambodia formed diplomatic ties to China which made the US mistrust them as an ally. Tensions increased when the North Vietnamese Army (NVA) began using Cambodian territory for military operations. The Chief of State of Cambodia over looked the NVA activities, but when the US would chase NVA troops across the Cambodia border back into North Vietnam, there were many protests that the US was violating the Geneva Accords. In 1965, Cambodia’s leader was certain the CIA was trying to overthrow him, so he began relationships with the communists and began receiving support from them. By late 1968, North Vietnamese forces were using key bases in Cambodia from which to launch attacks into South Vietnam. This prompted President Nixon to launch secret B-52 bombing of North Vietnam’s Cambodian bases. At the time there were estimated 36,000-60,000 communist troops in Cambodia. This led to an apparent US les coup that overthrew Cambodian chief of state, Sihamsuk, and brought General Lo Nol to power on March 18, 1970.When Lo Nol, the pro- US general, ordered NVA troops out of Cambodia they refused and a civil war broke out. Even as, the long 600 mile border between Cambodia and South Vietnam was fast becoming one huge communist base. This led to more US involvement in Cambodia including both attacks by troops in land and by US naval forces. President Nixon gave General a strict time limit that all US forces be removed by June 30, 1970.The US investment in Cambodia reached into its final stage after the signing of Paris Peace accords in January 1973. President Nixon, however, still continued military action in Cambodia until as late as 1975. When after the resignation of President Nol, the last US citizens were evacuated by helicopter.