One China Policy
The formula that there is only one China, meaning subtly different things to Beijing and Washington, that frames the entire Taiwan dispute.
Two governments, one phrase, and a deliberate refusal to say exactly what it means: that ambiguity is a large part of why the Taiwan Strait has stayed quiet for decades. Almost every country that deals with China signs on to some version of one China. What almost none of them spell out is whose China, and whether Taiwan is part of it. The gap between Beijing's version and Washington's is where the whole dispute lives.
Beijing's principle
The People's Republic of China calls its position the One China principle. It holds that there is only one China, that the PRC government in Beijing is its sole legal representative, and that Taiwan is an inalienable part of that China. Beijing treats acceptance of this principle as the non-negotiable price of diplomatic relations: states that recognize the PRC must break formal ties with Taipei. In 1971 the United Nations acted on that logic, passing Resolution 2758, which seated the PRC and expelled the representatives of Chiang Kai-shek, leaving Taiwan diplomatically isolated. Today only about a dozen states still formally recognize the Republic of China.
Washington's policy
The United States calls its own stance the One China policy, and the wording is chosen with care. When Washington normalized relations with Beijing in 1979 and cut official ties with Taipei, it acknowledged the Chinese position that there is one China and Taiwan is part of it, but it did not endorse it. That single verb, acknowledge rather than accept, is the hinge of American policy. The US keeps only unofficial relations with Taiwan, yet the Taiwan Relations Act of 1979 commits it to sell the island defensive arms and to treat any coercion of Taiwan as a grave concern. Washington takes no formal position on the ultimate question of sovereignty, insisting only that it be resolved peacefully and with the consent of Taiwan's people.
Strategic ambiguity
The result is a doctrine built on studied vagueness. The US declines to say whether it would fight to defend Taiwan, a posture known as strategic ambiguity, meant to deter Beijing from attacking while discouraging Taipei from declaring formal independence. Taiwan governs itself, elects its own leaders, and fields its own military, yet stops short of proclaiming the separate statehood that Beijing warns would mean war. The 1992 Consensus, a contested formula under which the two sides supposedly agreed there is one China while differing on what it means, is invoked and disowned depending on who is speaking. For now the deliberate blur holds. Its fragility is that it depends on no one demanding a straight answer, because the moment either side forces the phrase to mean only one thing, the peace it protects could break.