Political map of East Asia and the Western Pacific 27 January 1973 (Paris Peace Accords): By the late 1960s, US public opinion had swung strongly against involvement in the Vietnam War (Opposition to the U.S. involvement in the Vietnam War), a stance exacerbated when involvement spread to Laos (Laotian Civil War) and Cambodia (Cambodian Civil War). Meanwhile, the People's Republic of China clashed with the Soviet Union (Sino-Soviet border conflict), improving China's relations with the US (1972 Nixon visit to China) and eliminating the US fear of a single Communist bloc gaining control of Asia (Domino theory). These factors led to US President Nixon agreeing to withdraw from Vietnam and arranging the Paris Peace Accords, a cease fire between all parties.