Who Owns the Strait: The Legal Status of Taiwan's Waters and Why It Matters Now
The legal status of the Taiwan Strait has become an active diplomatic flashpoint rather than a settled background condition. The United States and its allies assert that the strait is an international waterway subject to the freedom of navigation that applies to straits used for international navigation. China asserts that the strait is Chinese internal waters, through which foreign military vessels do not have an automatic right of transit. These positions are irreconcilable, and the competition to establish which one is treated as authoritative by state behavior is a current, active dimension of the Taiwan Strait competition that operates below the threshold of military confrontation.
American freedom of navigation operations — naval transits conducted specifically to contest excessive maritime claims — have proceeded through the strait on a regular basis. The routine transits by US Navy vessels through the strait, conducted since the Trump administration’s decision to normalize them after a period of less frequent transits, signal American rejection of Chinese claims to restrict transit. Each transit produces a Chinese diplomatic protest and a PLA military response — typically surveillance and shadowing by PLA Air Force and PLAN vessels — that is calibrated to demonstrate Chinese awareness and assertiveness without forcing a confrontation. The ritual has become the primary mechanism through which both sides perform their legal positions.
The Chinese position on the strait is legally contestable but has internal consistency within its own framework. China claims that the strait is covered by its exclusive economic zone, which is accurate — the strait lies within 200 nautical miles of Chinese territory and thus falls within China’s EEZ claim under UNCLOS. China then argues that military vessels transiting another state’s EEZ require prior consent, which is China’s consistent if minority interpretation of UNCLOS. The argument is rejected by the United States, which interprets UNCLOS as granting high seas freedom of navigation within EEZs for warships. This is the majority interpretation and the one that American practice has consistently maintained.
Taiwan’s own legal position adds a layer of complexity. Taiwan is not a party to UNCLOS, having been displaced from the Chinese seat at the United Nations in 1971. Its maritime claims are thus made under customary international law rather than the treaty framework, and its ability to assert those claims against a PRC that controls the relevant institutions is practically limited. The waters on the Taiwanese side of the median line — the informal boundary that both sides had historically observed — are claimed by Taiwan as its own EEZ and continental shelf. China’s refusal to recognize the median line, most dramatically demonstrated by regular PLA Air Force crossings of it since 2020, asserts that the entire strait is Chinese in a way that Taiwan cannot effectively counter through legal mechanisms.
The practical import of the legal dispute is that it creates a framework within which Chinese authorities can claim legal justification for actions — stopping foreign vessels, boarding commercial ships, requiring prior consent for military transits — that the US and its allies reject but cannot prevent through legal mechanisms alone. If China were to enforce its claimed right to require prior consent for military transits through the strait, the American response would have to be either compliance — which would validate the Chinese legal position — or refusal backed by naval force — which transforms the legal dispute into a military confrontation. The Chinese position is designed to make both options costly.
The Taiwan relations legal architecture — the Taiwan Relations Act, the three communiqués, the six assurances, American recognition of the PRC government — was designed for a political environment that has changed substantially since 1979. American commitments to Taiwan have been maintained through this architecture without clarifying the legal status of the strait, the circumstances under which American military force would be used in Taiwan’s defense, or the legal framework for the arms sales that the Taiwan Relations Act requires. The ambiguity has been functional. It is becoming more difficult to sustain as Chinese legal claims become more assertive and the situations in which those claims could be enforced become more plausible.
The strait’s legal status is not merely an academic question. It is the normative battlefield on which the next phase of the competition will be partly fought.