In 1972, U.S. President Richard Nixon visited Mainland China, and met with Communist Party of China (CPC) Chairman Mao Zedong and Premier Zhou Enlai, then the two parties agreed on the "One-China" policy (i.e. the positions of then governments of the two sides across the Taiwan Strait "at that time" both claim there is only "one China" in the world).[13][14] In 1978 President Jimmy Carter's administration formally cut ties with the Republic of China (ROC) on Taiwan, establishing relations with the PRC. Since the severing of diplomatic relations, the Presidents of the United States and the Republic of China have never formally met or made calls in line with the policy. But the 1979 Act of Congress Taiwan Relations Act and the 1982 Six Assurances between the governments between U.S. and Taiwan have defined the substantial relations between the peoples of the United States and Taiwan.