The One China policy is a key cornerstone of Sino-US relations. It is the diplomatic acknowledgement of China's position that there is only one Chinese government. Under the policy, the US recognises and has formal ties with China rather than the island of Taiwan, which China sees as a breakaway province. China insists Taiwan is an inalienable part of one China. So, any country that wants diplomatic relations with mainland China must break official ties with Taipei. Since, the US established formal diplomatic ties with Beijing in 1979, it had to sever ties with Taiwan and closed its Taipei embassy. This has resulted in Taiwan's diplomatic isolation from the international community.