Political map of Russia & the former Soviet Union 17 November 1969 (Sino-Soviet Border Conflict): The Cuban Missile Crisis (1962) (Cuban Missile Crisis) had brought the world to the brink of nuclear war. To avoid this danger, the Soviet Union and United States began working to reduce tensions (D├ętente).    Meanwhile, however, the Soviet Union and China had drifted apart (Sino-Soviet split) and become rivals for leadership of the Communist (Communist) world. In 1969, they even engaged in armed clashes over their disputed border (Sino-Soviet border conflict).