Naval Operations and the Right to Operate Freely in the Taiwan Strait

By Raul (Pete) Pedrozo


A Turkish news report indicated that the transit of the Taiwan Strait by the USS Sampson (DDG 102) on April 26, 2022, triggered Chinese “counter-measures.” The report further indicated that the transit of the U.S. guided-missile destroyer was perceived by China as provocative and that such transits “intentionally sabotaged peace and stability in the region.” People’s Liberation Army-Navy (PLAN) ships and aircraft were positioned to the southwest and northeast of the strait to shadow the Sampson’s transit. Similar complaints are levied by China when a U.S. warship operates in the strait.

A statement released by the U.S. Seventh Fleet on April 26 countered the Chinese accusations, indicating that the U.S. warship had “conducted a routine Taiwan Strait transit through international waters in accordance with international law.” These transits demonstrate America’s “commitment to a free and open Indo-Pacific” and that U.S. ships and aircraft will fly, sail, and operate “anywhere international law allows.” What exactly does international law have to say about the rights of warships transiting the Taiwan Strait, and what does this imply for future operations and potential reactions?

The Taiwan Strait and UNCLOS

The average width of the Taiwan Strait is 97 nautical miles (180 kilometers); at its narrowest point, it is 70 nautical miles (130 kilometers) wide. Waterways, like the Taiwan Strait, that are greater than 24 nautical miles wide are considered geographic straits (UNCLOS, Article 36). In such straits, high seas freedom of navigation and overflight, and other lawful uses of the seas relating to such freedoms, apply in the water beyond the territorial sea, that is, the exclusive economic zone (EEZ) and/or high seas corridor (UNCLOS, Articles 58 and 87, and Part III). Thus, outside the territorial sea, U.S. warships and aircraft may conduct the same range of military operations in the strait that they conduct in foreign EEZs or on the high seas. Some of these lawful military activities include intelligence, surveillance, and reconnaissance (ISR) operations; launching and recovery of aircraft and other devices; submerged transits for submarines and other underwater devices; weapons exercises; military marine data collection and naval oceanographic surveys; underway replenishment; maritime interdiction operations; DPRK sanctions enforcement; maritime security operations; and flight operations.

The right of innocent passage applies in the areas of the strait along the coasts of China and Taiwan comprising their 12-nautical mile territorial seas (UNCLOS, Article 17) measured from baselines drawn in accordance with international law, which is normally the low-water line (UNCLOS, Article 5). Both China and Taiwan claim excessive straight baselines, which have been the subject of diplomatic and operational challenges by the United States since they do not comply with international law (UNCLOS, Article 7). If U.S. or other nations’ warships sail within 12 nautical miles of the low water line of the Chinese or Taiwanese coast, they must transit that area in innocent passage. Aircraft are not entitled to innocent passage and must remain outside of lawfully declared and recognized areas of national airspace. China’s incremental and incorrect characterization of the Taiwan Strait as either internal waters or an international strait, which would limit other nations’ high seas freedoms is another attempt to disrupt maritime operations that comply with the legal regime recognized in the rules-based international order.

PACIFIC OCEAN (Nov. 29, 2016) Arleigh Burke-class guided-missile destroyer USS Sampson (DDG 102) transits the Pacific Ocean. (U.S. Navy photo by Petty Officer 2nd Class Bryan Jackson/Released)


The assertion that the USS Sampson transit triggered Chinese countermeasures against the United States is puzzling. Legally, the term “countermeasures” refers to the peacetime law of state responsibility, not self-defense. States assume responsibility for their internationally wrongful acts, which consist of acts or omissions attributable to the state under international law and constitute a breach of an international obligation of the state. (ASR, Articles 1, 2). A state breaches an international obligation when an act of that state is not in conformity with what is required of the state by that obligation (ASR, Article 12). China may, therefore, take countermeasures in response to an internationally wrongful act committed by the United States, but only if the U.S. act constitutes a breach of an international obligation the United States owes to China (ASR, Article 49). Furthermore, any countermeasures would be directed at the United States at the national level and in any event must respect the sovereign immunity of U.S. warships and military aircraft.

There is no international obligation for any state to refrain from transiting or operating in the Taiwan Strait. The EEZ/high seas corridor of the strait is just another body of water where all states, including the United States, have a right under international law to engage in high seas freedoms of navigation and overflight, and other lawful uses of the seas relating to such freedoms. With regard to the latter, military operations, exercises, and activities have always been regarded as internationally lawful uses of the sea (Official Records, Vol. XVII, p. 244). Moreover, such military activities that are consistent with the principles of international law embodied in Article 2(4) and Article 51 of the United Nations Charter are not prohibited by United Nations Convention on the Law of the Sea (A/40/535, ¶ 188). Thus, the transit of the USS Sampson is not an internationally wrongful act and China may not take countermeasures against the United States.

Future Messaging

Given that there is an EEZ/high seas corridor in the strait, U.S. ships and aircraft can, and should, do more than just “transit” continuously and expeditiously through the strait and instead should exercise high seas freedoms in the EEZ. Ships and aircraft of all nations have the right to conduct normal operations in accordance with their high seas freedoms within the EEZ/high seas corridor of the Taiwan Strait. Statements, like the Navy’s April 26 release, give the impression that U.S. ships and aircraft are limited in what they can do while operating in the Taiwan Strait. Future U.S. operations in the strait should clearly demonstrate, through words and actions, that the waters and airspace of the Taiwan Strait are not, in any way, under Chinese control or jurisdiction.

Professor Raul (Pete) Pedrozo, Captain, USN, Ret., is the Howard S. Levie Professor on the Law of Armed Conflict, U.S. Naval War College, Stockton Center for International Law. Prior to his retirement from active duty after 34 years of service, he served in numerous positions advising senior military and civilian Defense officials, including as the senior legal advisor to Commander, U.S. Pacific Command. He also served as the Director of the Navy’s International and Operational Law Department in the Pentagon.

The views expresses are those of the author and do not necessarily reflect the views of the Department of Defense or the U.S. Naval War College.

Featured Image: The Taiwan Strait (Gallo Images)

One thought on “Naval Operations and the Right to Operate Freely in the Taiwan Strait”


    This piece restates Pedrozo’s and the U.S.’s interpretation of the relevant international law. But no matter how many times they do so, saying it does not necessarily make it acceptable to all other states.
    The article refers amply to the UN Convention on the Law of the Sea (UNCLOS). But the U.S. is not a party. Although the U.S. claims to abide by most of its provisions, it and China have different interpretations of key terms and clauses. Moreover, the Exclusive Economic Zone (EEZ) and its regime were created de nouveau by UNCLOS. The EEZ is sui generis and neither ‘high seas’ nor ‘international waters’.
    China and many other countries argue that the Convention is a series of package deals and that non-ratifiers like the U.S. are not entitled to the ‘benefits’ of particular tradeoffs while eschewing their part of the bargain. They contend, for example, that interpretation of key terms in the Convention relevant to freedom of navigation –like “other internationally lawful uses of the sea”, “abuse of rights, ”due regard”, “peaceful use/purpose”– are evolving rapidly through state practice and that non-ratifiers like the U.S. do not have the legitimacy to interpret them to their advantage—let alone unilaterally enforce their interpretations with warships and warplanes.
    The article refer to UNCLOS Articles 58 and 87, but conveniently neglects to mention the obligation to pay due regard to the rights and duties of the coastal state. Despite the article’s assertion, freedom of navigation in the EEZ is qualified by the due regard clause.
    More specifically, the article’s list of ‘freedoms’ in China’s EEZ in the Taiwan Strait includes ISR operations; launching and recovery of devices; weapons exercises; and military marine data collection and naval oceanographic surveys.
    Because of the due regard provision, such ‘freedoms’ depend on what specifically the warship or war plane is doing. For example, if it is undertaking cyber or electronic warfare (EW) this may be viewed as a threat or use of force –not allowed by the UN Charter let alone UNCLOS.
    Indeed, the U.S. views some cyber and EW attacks this way. It has agreed to a new clause in the ANZUS treaty that gives “cyber attacks the same weight” as missile or bomb attacks or physical invasions. So if the cyber and EW activities of the warships and warplanes in the EEZ constitute an ‘attack’, then what they are doing is illegal.
    Particularly relevant are active SIGINT activities conducted from aircraft and ships, some of which are deliberately provocative, intending to generate programmed responses. Other SIGINT activities intercept naval radar and emitters, enabling them to locate, identify and track (and thus plan electronic or missile attacks against) surface ships and submarines. Still others may interfere with communication and computer systems. These activities may involve far greater interference with the communication and defense systems of the targeted coastal state then any traditionally passive intelligence gathering activities conducted from outside national territory. China thinks that some such activities are not consonant with UNCLOS.
    Another relevant question is “whether such intelligence activities can be deemed inherently hostile to the security interest of the coastal state so as to make it impossible or difficult for the state conducting the intelligence activities to respect either the “peaceful purposes” limitation or the “due regard” limitation.” The UNCLOS negotiators apparently thought it necessary to retain this provision – even in the face of a Singapore proposal to delete it because it was unnecessary if the Convention clearly gives only jurisdiction over resources [in the EEZ] to the coastal state.”
    The article assumes that military surveys are not subject to the prior consent regime for marine scientific research. But this argument can be put to rest by a plain reading of UNCLOS Article 258? It provides that “the deployment and use of any type of scientific research installation or equipment in any area of the marine environment shall be subject to the same conditions as are prescribed in this Convention for the conduct of marine scientific research in any such area.” It seems difficult to avoid the conclusion that the deployment of such equipment in a foreign EEZ requires the consent of the coastal state.
    Simple naval transit and maneuvers are part of the freedom of navigation. But China may argue that extended tests of weapons, such as laying of depth charges, launching torpedoes, live fire exercises or the covert laying of arms within an EEZ violate the duty to pay ‘due regard’ to the rights and duties of the coastal state, especially their duty to protect the environment including its fish and mammals. Moreover, the legality of military maneuvers and missile exercises that temporarily prevent other states from using part of their EEZ remains unresolved.
    Consider the US reaction if China were to repeatedly undertake such activities in the US EEZ off its west or east coast or in the Gulf of Mexico. While it may not legally object, it surely would consider this provocative, monitor them closely, even harass the assets undertaking the activities and plan “countermeasures” in the event of an attack.
    The Convention provides that in cases where it does not specifically attribute rights or jurisdiction to the coastal or other states within the EEZ, any dispute between the states parties should be resolved on the basis of equity and in the light of all the relevant circumstances, taking into account the respective importance of the interests involved to the parties as well as to the international community as a whole (Article 59). So the question may become: which is more equitable or more valuable to the international community – the right to spy, ‘prepare the battle field’ and threaten– or the right to ban such activities in one’s EEZ.
    We probably will never know the definitive legal answer because the U.S. is not a party to UNCLOS and can neither avail itself of- or be subjected to- its dispute settlement mechanisms. This may be one reason why the U.S. has to resort to gunboat diplomacy to assert its interpretations.
    Such disputes imply that certain UNCLOS provisions formulated in a very different political and technological era must be interpreted in the light of these new circumstances – or renegotiated. Any such negotiations – with a weakened U.S, a hostile Russia and a rising China – would likely have very different results than before when the U.S. and the Soviet Union joined diplomatic forces to strongly influence the freedom of navigation provisions in favor of maritime powers. This is perhaps why the article beats the drum of the past hoping that those interpretations of these provisions will be static. But as international law evolves, this may be whistling by the graveyard of such legal theories.
    Mark J. Valencia
    Adjunct Senior Scholar
    National Institute for South China Sea Studies
    Haikou, China
    *This article was written and submitted in response to Pedrozo’s piece referenced above but the editors at CIMSEC and The Maritime Executive did not respond.

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