Sino-Soviet border conflict
This became an especially important concern for the People's Republic of China after the Sino-Soviet border conflict of 1969. The PRC was diplomatically isolated and the leadership came to believe that improved relations with the United States would be a useful counterbalance to the Soviet threat. Zhou Enlai, the Premier of China, was at the forefront of this effort with the committed backing of Chairman Mao Zedong. In 1969, the United States initiated measures to relax trade restrictions and other impediments to bilateral contact, to which China responded. However, this rapprochement process was stalled by the Vietnam War where China was supporting the enemies of the United States. Communication between Chinese and American leaders, however, was conducted through Romania, Pakistan and Poland as intermediaries.