During the Vietnam War China backed North Vietnam with arms and aid, assisting the North in its eventual victory. However after the war ended in 1975 relations deteriorated over several contentious issues, such as Vietnam's siding with the USSR in the Sino-Soviet split, China's rapprochement with the USA under President Richard Nixon, disputes over the maritime border, and China's alleged support for minority insurgent groups along the border. The final straw came after Vietnam invaded Cambodia and removed the Chinese-backed Khmer Rouge government in 1978. The following year the brief Sino-Vietnamese War broke out along the border; though China withdrew after only three weeks it remained in occupation of small strategic areas along the frontier, and low-level skirmishes along the border continued throughout the 1980s.