The Sino-Soviet border conflict, also known as the Sino-Soviet crisis, was a seven-month undeclared military conflict between the Soviet Union and China in 1969, following the Sino-Soviet split. The most serious border clash, which brought the world's two largest socialist states to the brink of war, occurred near Damansky (Zhenbao) Island on the Ussuri (Wusuli) River in Manchuria. Clashes also took place in Xinjiang.