Can the United States Make the Strait of Hormuz U.S. Territory? International Law Explained
- Edmarverson A. Santos
- 1 day ago
- 16 min read
Introduction
The Strait of Hormuz entered an unusual legal controversy in August 2026 when President Donald Trump stated that he would declare the waterway U.S. territory after previously claiming that the United States exercised “total control” over it. The remark was political rather than a formal act purporting to transfer sovereignty, but it raises a concrete question of international law: could the United States lawfully acquire sovereignty over the Strait of Hormuz through declaration or military control? The short answer is no. A presidential statement, without an independent legal basis for territorial change, cannot transfer Iranian or Omani territorial waters to the United States (Reuters, 2026a; Reuters, 2026b).
Iran and Oman are the coastal states bordering Hormuz. Their sovereignty over their respective territorial seas is not displaced by the Strait’s exceptional importance to international navigation. International law instead limits how coastal sovereignty may be exercised where a strait connects maritime areas and serves international shipping. Foreign vessels may enjoy legally protected passage while the waters through which they travel remain subject to the sovereignty or jurisdiction of the bordering states.
UNCLOS reflects this arrangement. Article 34 preserves the sovereignty or jurisdiction of states bordering straits, while Part III regulates passage through straits used for international navigation (United Nations, 1982). The underlying distinction predates the Convention. In Corfu Channel, the International Court of Justice recognized a customary peacetime right of innocent passage through a strait connecting two parts of the high seas and used for international navigation (ICJ, 1949). UNCLOS later developed the broader regime of transit passage, which includes navigation and overflight and should not be treated as identical to the rule applied by the Court in 1949.
The treaty position surrounding Hormuz adds a genuine doctrinal complication. Oman is a party to UNCLOS, whereas Iran signed but has not ratified the Convention, and the United States remains a non-party. Iran has questioned whether the treaty-based right of transit passage, including the regime reflected in Article 38, automatically benefits non-parties as customary international law. The United States has long maintained that the Convention’s principal navigation and overflight rules reflect customary law. That disagreement concerns the legal basis and scope of passage through the Strait; it does not provide Washington with a competing claim to sovereignty over Iranian or Omani territorial waters.
Military power does not resolve the territorial question. Naval superiority may allow a state to patrol routes, escort vessels, influence shipping, or exercise substantial factual control over maritime movements. Sovereignty over territorial waters depends on legal title, not simply on the capacity to dominate an area at a particular moment. Strategic necessity or military effectiveness cannot substitute for the legal requirements governing territorial status.
Coercion would raise an additional body of rules. Article 2(4) of the UN Charter prohibits the threat or use of force against the territorial integrity or political independence of another state (United Nations, 1945). The Friendly Relations Declaration, adopted by the General Assembly in Resolution 2625, articulates the principle that territory may not be acquired through the threat or use of force and that resulting territorial acquisitions should not be recognized as lawful (UN General Assembly, 1970). The declaration is not itself a treaty, but its formulation is central to the international legal treatment of territorial acquisition by force.
Trump’s statement consequently presents a narrower legal problem than the broader geopolitical struggle over who can influence navigation through Hormuz. Sovereignty, passage rights, military control, and the lawful use of force are governed by different rules and cannot be collapsed into a single concept of “control.” The United States may possess significant security and navigational interests in the Strait, but neither unilateral declaration nor superior military power can, without a valid legal basis, convert those interests into sovereignty over the territorial waters of Iran or Oman.
1. Trump’s Territorial Statement on Hormuz
President Donald Trump introduced an unusual territorial dimension into the dispute over the Strait of Hormuz when he said in August 2026 that he would declare the waterway U.S. territory. The statement followed his earlier assertion that the United States had “total control” of the Strait amid ongoing U.S. military operations and severe disruption to commercial navigation (Reuters, 2026a; Reuters, 2026b). A White House official subsequently characterized the territorial remark as a joke, and it was not itself a legal instrument capable of altering sovereignty (Wall Street Journal, 2026). Its significance for international law lies in the proposition it raises rather than in any completed change to the territorial status of Hormuz.
The language of territorial acquisition must be distinguished from claims concerning naval or operational control. A state may have the military capacity to patrol a maritime route, escort vessels, deter particular forms of navigation, or exert considerable influence over commercial shipping. Trump’s earlier claim of “total control” was itself disputed by Iran, which asserted that navigation through Hormuz remained under Iranian management and control (Reuters, 2026c). Reports of sharply reduced commercial traffic, Iranian restrictions and attacks, and U.S. military operations further show that factual control of the waterway cannot be reduced to a single uncontested assertion.
The legal question created by Trump’s territorial language is narrower. It is not whether the United States has sufficient naval power to shape events in Hormuz, but whether military superiority, navigational interests, or unilateral presidential action could supply a lawful basis for U.S. sovereignty over any part of the Strait. Answering that question first requires identifying the states that presently exercise sovereignty over its territorial waters and the effect that the international navigation regime has on their authority.
2. Who Has Sovereignty in the Strait of Hormuz?
Iran borders the Strait of Hormuz to the north and Oman to the south. The territorial sea adjacent to each coastal state is subject to that state’s sovereignty under the general law of the sea. Article 2 of UNCLOS provides the conventional formulation of this rule, extending coastal-state sovereignty beyond land territory and internal waters to the territorial sea, including the airspace above it and the seabed and subsoil beneath it (United Nations, 1982, art. 2). The special rules governing international straits qualify the exercise of this authority; they do not eliminate the territorial status of the waters concerned.
Article 34 of UNCLOS makes this relationship explicit. The regime governing passage through international straits does not affect the legal status of the waters forming those straits or the sovereignty or jurisdiction exercised by bordering states (United Nations, 1982, art. 34). Hormuz is consequently not an internationalized territory merely because it is an essential route for international shipping. Foreign states may possess substantial navigational rights without acquiring sovereign authority over the territorial seas through which their vessels travel.
Iran and Oman have also concluded bilateral arrangements concerning their maritime boundary. Their 1974 agreement delimited the continental shelf between them and entered into force in 1975 (Iran–Oman Continental Shelf Agreement, 1974). Its scope is important. The agreement expressly provides that the delimitation does not affect the legal status of the waters above the continental shelf or the airspace above them. It should not be treated as a comprehensive settlement of every question concerning territorial-sea sovereignty or navigational rights in the Strait.
The result is a legal geography in which coastal sovereignty and international navigation coexist. Iran and Oman exercise the relevant sovereignty over territorial waters on their respective sides of Hormuz, while international law constrains how that authority may be exercised against vessels and aircraft entitled to passage. The extent of those passage rights, particularly given the different treaty positions of Iran, Oman, and the United States, requires a separate examination of the law governing international straits.
3. Sovereignty and Transit Passage Through the Strait
UNCLOS Part III establishes the principal treaty regime for straits used for international navigation. Article 37 applies the transit-passage provisions to straits connecting one part of the high seas or an exclusive economic zone with another part of the high seas or an exclusive economic zone. Article 38 then provides a right of transit passage, understood as freedom of navigation and overflight solely for the purpose of continuous and expeditious transit through the strait (United Nations, 1982, arts 37–38). The regime is broader than ordinary innocent passage because it expressly protects overflight and accommodates navigation associated with the normal operation of ships and aircraft.
Transit passage is accompanied by defined obligations. Under Article 39, ships and aircraft must proceed without delay, refrain from any threat or use of force against the sovereignty, territorial integrity, or political independence of states bordering the strait, and avoid activities other than those incident to their normal modes of continuous and expeditious transit, except where necessary because of force majeure or distress (United Nations, 1982, art. 39). States bordering a strait retain regulatory authority in the fields identified by Article 42, including navigational safety, pollution prevention, fishing by foreign vessels, and specified customs, fiscal, immigration, and sanitary matters. Such laws may not discriminate among foreign ships or operate in practice to deny, hamper, or impair transit passage.
UNCLOS also limits the capacity of coastal states to interrupt qualifying passage. Article 44 requires states bordering straits not to hamper transit passage, obliges them to give appropriate publicity to dangers to navigation or overflight of which they have knowledge, and provides that there shall be no suspension of transit passage (United Nations, 1982, art. 44). These restrictions demonstrate why sovereignty over territorial waters in an international strait does not carry the same freedom of exclusion that a coastal state might otherwise expect within its territorial sea.
The modern transit-passage regime must be distinguished from the rule recognized by the International Court of Justice in Corfu Channel. The 1949 case concerned the passage of British warships through Albanian territorial waters. The Court held that, in peacetime, states possessed a customary right to send warships through straits used for international navigation between two parts of the high seas, provided that the passage was innocent (ICJ, 1949). The Court relied on the geographical function of the Corfu Channel and its use for international navigation rather than on the later treaty concept of transit passage.
Corfu Channel did not establish the broader UNCLOS regime subsequently codified in Part III. The distinction is particularly important for Hormuz because Iran has signed but not ratified UNCLOS and the United States is not a party. The existence of customary navigational rights is not the same question as whether every element of the treaty-based transit-passage regime binds non-parties. That disagreement affects the legal basis and scope of U.S. navigation through the Strait, but it does not alter the underlying sovereignty of Iran and Oman over their respective territorial waters.
4. Iran, Oman, the United States, and UNCLOS
The legal position in Hormuz is complicated by the different relationships of Iran, Oman, and the United States with UNCLOS. Oman is a party to the Convention. Iran signed it in 1982 but has not ratified it, while the United States remains a non-party. Treaty obligations under UNCLOS bind its parties as treaty law. A non-party may nevertheless be bound by a parallel rule of customary international law where the requirements for custom are satisfied, but the customary obligation exists independently of the treaty rather than because the Convention itself has become applicable to the non-party.
Iran addressed this distinction expressly when signing UNCLOS. Its declaration maintained that some provisions resulted from negotiated compromise and should not automatically be regarded as codifying pre-existing customary international law. Iran specifically referred to the right of transit passage under Article 38 and questioned whether treaty-created rights of that kind could be invoked by states that were not parties to the Convention (United Nations Treaty Collection, 1982). The United States has long advanced the opposing position, maintaining that the principal UNCLOS rules concerning navigation and overflight, including transit passage through international straits, reflect customary international law. The disagreement is significant because both Iran and the United States stand outside the Convention, yet each advances a different account of the customary rules governing navigation through Hormuz.
Oman’s declarations add another layer. Oman has affirmed its sovereignty over its territorial sea and has also declared that foreign warships require prior permission for innocent passage through Omani territorial waters. UNCLOS, however, generally prohibits reservations unless the Convention expressly permits them. Article 310 allows states to make declarations or statements when signing, ratifying, or acceding to UNCLOS only if those declarations do not purport to exclude or modify the legal effect of the Convention (United Nations, 1982, arts 309–310). Oman's declarations must be interpreted within that limitation. A unilateral declaration cannot, by itself, convert an applicable transit-passage regime into one dependent on prior coastal-state authorization.
These competing positions affect the legal basis on which navigational rights may be invoked in Hormuz, particularly where one or more states are not parties to UNCLOS. They do not create a dispute about who possesses sovereignty over the relevant territorial waters. A customary right of navigation and a treaty right of transit passage regulate the use of a strait; neither supplies a third state with sovereign title over the waters through which passage occurs.
5. Can the United States Acquire Sovereignty Over Hormuz?
A unilateral American declaration could not extinguish Iranian or Omani sovereignty over their territorial waters. International law contains no rule by which a third state acquires sovereignty simply by announcing that another state’s territorial sea has become its own. The special navigational status of the Strait of Hormuz does not place those waters outside the sovereignty of the coastal states. Rights of passage regulate access and movement through the Strait; they do not create territorial rights in favor of the states exercising them.
Maritime arrangements can change lawfully, but they require a recognized legal basis. Coastal states may delimit maritime boundaries by agreement, submit disputes to adjudication or arbitration where jurisdiction exists, or adjust legal arrangements through other consensual processes recognized by international law. The Iran-Oman continental-shelf agreement illustrates the role of bilateral consent in defining maritime entitlements. A unilateral proclamation by a third state performs none of those functions and cannot substitute for the consent or other legal basis required to alter existing maritime sovereignty.
The use of force cannot cure that defect. Article 2(4) of the UN Charter prohibits the threat or use of force against the territorial integrity or political independence of another state (United Nations, 1945). The Friendly Relations Declaration adopted in General Assembly Resolution 2625 articulates the principle that territorial acquisition resulting from the threat or use of force must not be recognized as lawful (UN General Assembly, 1970). The International Court of Justice has likewise treated the inadmissibility of territorial acquisition through force as an established principle of international law (ICJ, 2004). Military capacity might enable a state to impose control in practice, but it cannot transform an otherwise invalid territorial claim into lawful sovereignty.
6. Military Control and Territorial Sovereignty
International law does not treat effective military power as a source of sovereign title. A state may acquire extensive practical influence over a maritime area through naval patrols, escorts, interceptions, exclusion measures, or other military operations, yet the legal status of the waters does not change merely because another state can exercise greater force there. The legality of those operations and the existence of sovereignty are separate questions governed by different rules.
The distinction is familiar elsewhere in the law of armed conflict. Belligerent occupation on land depends on the effective authority exercised by hostile forces, but occupation does not transfer sovereignty to the occupying power. The analogy is useful for Hormuz only at the level of principle: territorial waters are not thereby treated as territory subject to the Hague law of belligerent occupation. Rather, the occupation regime demonstrates more generally that international law can recognize extensive factual control while preserving the underlying sovereignty of another state.
Naval warfare provides a similar example. In an international armed conflict, a blockade may be used to restrict maritime access if the applicable requirements of the law of naval warfare are satisfied. Even a legally valid blockade regulates access; it does not transfer sovereignty over the coast, territorial sea, or maritime approaches affected by it. The same separation applies to naval escorts, interceptions, and other operations. Their legality must be assessed under the UN Charter, the law of the sea, and, where applicable, the law of armed conflict and naval warfare.
Claims that a state “controls” the Strait of Hormuz must consequently be interpreted with care. Operational dominance may describe military capability, the ability to influence commercial navigation, or temporary superiority in a particular area. None of those conditions determines who holds sovereignty over the territorial waters forming the Strait. Iranian and Omani sovereignty cannot be displaced merely by the presence or effectiveness of U.S. naval forces.
7. Threats of Force Against Oman Under International Law
The Hormuz dispute acquired an additional legal dimension when President Trump threatened military action against Oman if it obstructed U.S. objectives concerning the Strait. The statement was made while Muscat was engaged with Tehran over arrangements concerning navigation through Hormuz (Reuters, 2026d). Although this episode is secondary to the territorial question at the center of the article, an express threat to bomb another state engages a distinct body of international law.
Article 2(4) of the UN Charter requires states to refrain from the threat or use of force against the territorial integrity or political independence of another state, or in any other manner inconsistent with the purposes of the United Nations (United Nations, 1945). In the Nuclear Weapons advisory opinion, the International Court of Justice linked the legality of a threat to the legality of the force contemplated: if the proposed use of force would be unlawful, the corresponding threat to employ it would likewise be unlawful (ICJ, 1996). The relevant inquiry is accordingly whether the military action being threatened could itself rest on a lawful basis.
On the publicly reported circumstances, disagreement with Oman over negotiations concerning Hormuz would not itself supply such a basis. Article 51 preserves the right of individual or collective self-defense if an armed attack occurs, subject to the applicable requirements of necessity and proportionality. Political opposition to an Omani agreement with Iran, resistance to U.S. policy, or interference with a preferred diplomatic outcome does not, without additional facts, amount to an armed attack against the United States.
Other legal bases must also be kept distinct. The Security Council may authorize force under the Charter, while military operations within another state’s territory or territorial waters may occur with that state’s valid consent when they remain within the scope of the consent given. Neither situation is equivalent to threatening coercive military action against the consenting state itself. Nothing in the law governing international navigation creates a separate entitlement to attack Oman merely because Washington objects to the way Muscat seeks to regulate or negotiate questions concerning Hormuz.
8. What the United States May Lawfully Do in Hormuz
The absence of U.S. sovereignty over the Strait does not leave Washington without rights under international law. The United States has long maintained that the principal UNCLOS rules on navigation and overflight, including transit passage through international straits, reflect customary international law. On that legal position, U.S. ships and aircraft may claim the customary equivalent of UNCLOS transit-passage rights through qualifying straits even though the United States is not a party to the Convention. Iran contests important aspects of that characterization, so the customary basis and precise scope of those rights should not be presented as entirely uncontested.
Whatever their source, navigational rights do not confer jurisdiction to administer the Strait. Under the UNCLOS model, transit passage protects continuous and expeditious navigation and overflight while preserving the sovereignty or jurisdiction of the bordering states (United Nations, 1982, arts 34, 38–44). A state exercising passage rights does not acquire authority to determine the territorial status of the waters, replace coastal-state institutions, or impose sovereign control simply because its vessels are entitled to transit.
Maritime-security activity requires a more fact-specific assessment. Naval escorts and cooperative measures designed to protect commercial shipping may be compatible with international law when conducted consistently with applicable navigational rights, coastal-state sovereignty, and any consent on which an operation relies. Interceptions, attacks, or other coercive measures raise additional questions under the law of the sea, the UN Charter, and, where applicable, the law of armed conflict and naval warfare.
Freedom of navigation is not a freestanding authorization to use armed force. Any use of force in international relations must comply with the Charter. Where the United States invokes self-defense, the requirements of Article 51 and applicable customary law must be satisfied; where it relies on Security Council authority, the relevant resolution must provide the necessary legal basis. Washington may assert navigational rights and protect shipping through measures permitted by international law, but those rights cannot be converted into a general power to govern, annex, or claim sovereignty over Hormuz.
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Conclusion
The United States cannot make the Strait of Hormuz U.S. territory by unilateral presidential declaration. The waters forming the Strait remain subject to the sovereignty or jurisdiction of Iran and Oman according to the applicable law of the sea. Their authority is constrained by international navigational rules, but those limitations do not transfer sovereign rights to the states whose vessels use the waterway.
The more difficult legal questions concern passage and security rather than territorial title. The United States maintains that the UNCLOS transit-passage regime substantially reflects customary international law, while Iran disputes important elements of that position. Particular U.S. maritime or military measures must consequently be assessed according to their own legal basis, including the law of the sea, Article 2(4) of the UN Charter, the law of self-defense, and any applicable rules of armed conflict.
The language of “control” obscures these distinctions. A state may possess the military capability to influence navigation through Hormuz without acquiring sovereignty over its territorial waters, just as a right of passage does not create a right of administration. International law separates access, operational power, and sovereign title. Neither superior naval force nor a unilateral declaration is sufficient to turn the Strait of Hormuz into U.S. territory.
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