THE DEEP BRIEF · ISSUE 03
Iran, the United States, and the erosion of navigational order in the world's most contested waterway
"The high seas being open to all nations, no state may validly purport to subject any part of them to its sovereignty."
— ICJ, Corfu Channel Case (United Kingdom v. Albania), 1949
Introduction: The Strait as a Test of Maritime Order
In the spring of 2025, something shifted in the Strait of Hormuz that was not fully captured by the headlines it generated. Iranian forces seized vessels, restricted navigational corridors, intensified maritime interdictions, and — in a development that received far less attention than it deserved — began publicly redefining the surrounding maritime space not merely as a navigational chokepoint, but as a broader zone of Iranian strategic management extending from Jask to Siri Island.
That reframing mattered because it represented more than military signalling. It was an attempt to convert operational control into jurisdictional legitimacy.
The Strait of Hormuz has long occupied a paradoxical position within international order. It is among the most strategically indispensable waterways in the world, yet the legal architecture governing it rests upon principles designed precisely to prevent indispensable geography from becoming a tool of coercive control. The modern law of the sea emerged in part from the recognition that certain maritime corridors could not remain subject solely to the political discretion of the states bordering them. The economic circulation of the international system required something more durable than temporary strategic restraint.
What is now unfolding in Hormuz is therefore not simply a regional confrontation between Iran and the United States, nor merely another episode in the long militarisation of the Persian Gulf. It is increasingly a test of whether international maritime law still meaningfully constrains strategically vital geography once major-power confrontation intensifies.
The immediate legal question — whether particular Iranian actions are lawful — matters less than the larger structural question emerging beneath it:
Who governs a strategic waterway in practice once legal entitlement and operational control begin to diverge?
That question extends well beyond the Gulf. The answer will shape the future governance of maritime chokepoints globally.
The Geography of Strategic Leverage
The Strait of Hormuz is approximately thirty-eight kilometres wide at its narrowest point. Through it passes roughly one-fifth of the world’s traded oil and a substantial proportion of globally traded liquefied natural gas. The commercial shipping channels themselves are far narrower — two transit lanes of approximately three kilometres each, separated by a buffer zone.
The geography is narrow. The strategic implications are not.
Hormuz functions less as an isolated maritime passage than as a circulatory artery of the global economy. Energy markets, insurance systems, freight pricing, naval deployment patterns, and broader geopolitical stability all remain acutely sensitive to disruptions within the Strait.
Yet the strategic significance of Hormuz does not arise solely from commerce. Strategic waterways have historically operated as sites where universal legal principles collide with territorial sovereignty and asymmetrical power.
The Ottoman Straits regime, the Suez Canal, the Panama Canal, the Danish Straits, and the Corfu Channel dispute all exposed variations of the same recurring tension: maritime powers seek guaranteed openness, while strategically situated coastal states seek leverage over the geography they inhabit.
Throughout modern history, maritime powers have generally universalised navigational rights during periods in which they dominated the international order. Coastal powers, by contrast, have often sought to regionalise maritime control when unable to compete symmetrically within that order.
Hormuz sits precisely at that intersection.
The Strait is bordered by Iran to the north and Oman to the south. That shared geography matters more than many contemporary analyses acknowledge. Discussions of Hormuz frequently reduce the issue to a bilateral US-Iran confrontation, overlooking the role of Oman in sustaining the operational and diplomatic equilibrium of the Strait.
Muscat has historically functioned as a mediator between Iran and Western powers, maintaining channels of communication even during periods of heightened confrontation. Oman’s strategic ambiguity has long served as a stabilising mechanism within Gulf diplomacy.
That position is becoming increasingly consequential.
Any durable governance framework for Hormuz ultimately depends not only upon naval deterrence or legal doctrine, but upon whether regional actors continue to preserve enough diplomatic space to prevent operational confrontation from hardening into permanent maritime fragmentation.
The Legal Architecture of Transit Passage
The modern legal framework governing strategic straits emerged from the broader post-war effort to stabilise international circulation through institutionalised maritime order.
The United Nations Convention on the Law of the Sea (UNCLOS), which entered into force in 1994, established a specific regime governing straits used for international navigation. Part III of the Convention codifies the principle of transit passage.
Under transit passage, ships and aircraft enjoy the right of continuous and expeditious transit through qualifying straits. That right cannot be suspended by the coastal state.
The distinction between transit passage and innocent passage is foundational.
Under innocent passage, the coastal state retains broader authority to regulate maritime movement in the interest of security, public order, and territorial integrity. Passage may be conditioned or restricted under certain circumstances.
Transit passage significantly narrows that discretion.
The regime was designed precisely to prevent strategically situated coastal states from converting geography into coercive leverage over international circulation.
The prevailing international position is that Hormuz falls squarely within the transit passage framework. The Strait is used continuously for international navigation. No viable alternative route exists that avoids substantial strategic and economic disruption. The legal criteria established under UNCLOS are generally understood to be satisfied.
Iran rejects that interpretation.
Although Tehran signed UNCLOS, it never ratified the Convention. Through domestic legislation — including the 1993 Marine Areas Act — and through subsequent operational practice, Iran has continued to apply a framework closer to innocent passage within what it considers its territorial waters surrounding the Strait.
This disagreement is not merely technical. It determines whether Hormuz is understood as:
— an internationally guaranteed navigational corridor whose openness cannot be conditioned by regional politics; or
— a strategically managed maritime zone whose accessibility remains contingent upon Iran’s security calculations.
That distinction lies at the centre of the current confrontation.
For much of the post-UNCLOS period, this disagreement existed largely as a reserved legal asymmetry — acknowledged but operationally contained.
What has changed in recent years is that Iran has increasingly sought to operationalise its preferred interpretation rather than merely preserve it as a dormant legal position.
That shift carries implications far beyond the Gulf.
The Expanding Operational Zone
Among the most analytically significant developments of the current period is the gradual spatial expansion of Iranian maritime claims.
Iranian officials and IRGC commanders have increasingly described the relevant operational space not as the narrow transit corridor traditionally associated with the Strait itself, but as a broader strategic maritime zone extending significantly beyond the conventional navigational framework.
This matters because contemporary maritime order depends not only upon treaty language, but upon accumulated patterns of state practice.
Customary international law develops, in part, through repeated operational behaviour combined with the reactions — or failures of reaction — by other states.
This process unfolds slowly. But it is real.
When a state persistently acts as though a broader jurisdictional framework applies, and when other actors fail to contest that behaviour effectively over time, operational realities can begin gradually reshaping legal expectations.
Iran’s expanding conception of Hormuz therefore represents more than a temporary security posture. It is a long-term attempt to widen the gap between internationally recognised navigational entitlement and operationally enforced maritime control.
The international response has thus far remained largely reactive.
Naval patrols, diplomatic communiqués, coalition statements affirming freedom of navigation, and episodic freedom-of-navigation operations continue to restate the existing legal order. European and Asian governments have repeatedly reaffirmed the applicability of international maritime law and the transit passage regime.
Yet statements affirming legal principles do not themselves resolve the underlying contest.
What Iran appears increasingly to be testing is whether operational control can gradually outpace institutional response without triggering the level of sustained confrontation necessary to force a definitive legal reckoning.
That dynamic reflects a broader feature of contemporary geopolitical competition.
Many modern disputes no longer seek immediate formal revision of international law. Instead, they seek to create persistent operational ambiguities large enough that existing legal frameworks become progressively more difficult to enforce in practice.
Competing Legal Exceptionalism
The current confrontation is frequently framed as a dispute between Iran and international law.
The reality is institutionally more complex.
The United States itself is not a party to UNCLOS. Washington signed the Convention but never ratified it. Yet the United States simultaneously acts as the principal guarantor of the navigational freedoms codified within the Convention, conducting freedom-of-navigation operations, maintaining naval deployments, and asserting transit passage rights across the global maritime system.
The American position is not legally incoherent.
Washington argues that the relevant navigational provisions of UNCLOS reflect customary international law binding upon all states regardless of treaty ratification.
Iran’s position differs in important respects.
Tehran does not merely reject treaty obligation. It disputes the applicability of the transit passage regime itself within Hormuz.
The result is therefore not symmetrical hypocrisy, but competing forms of legal exceptionalism operating under conditions of strategic confrontation.
This distinction matters.
The United States continues to defend the universal applicability of navigational openness even while remaining outside the treaty framework formally codifying it. Iran, by contrast, seeks to reinterpret the scope of navigational openness in ways that expand coastal state discretion within strategically vital waters.
Both positions expose structural tensions within contemporary international law.
Modern maritime order depends less upon universal legal consensus than upon a broader convergence between legal principle, strategic interest, commercial necessity, and institutional enforcement capacity.
International law persists where powerful actors continue to perceive the underlying system as beneficial. It weakens where strategic incentives increasingly favour reinterpretation, selective compliance, or operational circumvention.
Hormuz is revealing those tensions with unusual clarity.
Governance Through Risk
The most consequential development in Hormuz may ultimately prove to be neither vessel seizure nor direct military confrontation.
It may instead be the emergence of governance through risk generation.
The Strait does not need to be formally closed in order to become functionally inaccessible.
During periods of heightened confrontation in 2025 and 2026, marine insurers withdrew or restricted coverage for vessels transiting the region. Tanker operators suspended or rerouted shipments. Freight costs surged. Crews exercised contractual refusal rights. Automatic Identification System transmissions became inconsistent as vessels sought to reduce operational visibility.
None of this required a formal declaration of closure.
The Strait remained legally open.
Yet commercial circulation began deteriorating nonetheless.
This development exposes a critical limitation within the traditional architecture of maritime law.
The law of transit passage was designed primarily to prevent explicit denial of passage by coastal states. It assumes that the principal threat to navigational freedom is formal prohibition.
The emerging threat is more subtle.
Modern chokepoints may increasingly be governed through calibrated instability severe enough to alter commercial viability without crossing the threshold that would trigger decisive institutional or military response.
In this environment, maritime governance shifts from courts and treaty interpretation toward insurers, freight markets, naval signalling, private risk assessment, and operational uncertainty.
Legal rights persist formally while circulation deteriorates practically.
That distinction may become one of the defining institutional characteristics of twenty-first century maritime competition.
The governance of strategic waterways increasingly depends not only upon whether ships possess a legal right to transit, but upon whether the surrounding ecosystem of insurance, logistics, commercial confidence, and operational predictability remains intact enough for transit to remain economically viable.
The implications extend far beyond Hormuz.
The Red Sea, the Bab-el-Mandeb, the South China Sea, Arctic shipping routes, and even future undersea cable governance may all become increasingly shaped by this hybrid model in which law, commercial risk systems, and strategic coercion jointly determine practical accessibility.
International law was not designed for a world in which navigational freedom could be eroded incrementally through sustained uncertainty rather than formally denied outright.
That is the world now emerging.
The Monetisation of Strategic Geography
Iranian discussions regarding the imposition of fees or tolls on vessels transiting Hormuz introduce an additional structural challenge to the existing maritime order.
UNCLOS sharply restricts the ability of coastal states to impose charges on foreign vessels exercising navigational rights except under narrowly defined circumstances involving specific services rendered.
The principle underlying these restrictions is foundational.
Strategic geography cannot simply be converted into sovereign rent extraction.
Historically, canal toll systems such as those governing the Suez and Panama Canals emerged within treaty frameworks that combined revenue authority with guaranteed access obligations.
Hormuz is fundamentally different.
No comparable treaty regime grants Iran authority to monetise transit passage through the Strait.
The significance of the proposal therefore lies less in its immediate legality than in the precedent it could establish if operationally normalised.
If commercial operators begin paying for secure transit through coercively managed waterways, the governing logic of strategic chokepoints begins to shift.
Navigational freedom gradually transforms from a universally protected legal entitlement into a transactional arrangement shaped by coercive leverage.
The implications would extend well beyond the Gulf. Comparable claims could eventually emerge elsewhere:
— the Malacca Strait;
— the Bab-el-Mandeb;
— the Turkish Straits;
— future Arctic corridors;
— or strategically significant passages within contested maritime zones.
The issue is therefore not simply whether a particular toll proposal violates maritime law.
The larger issue is whether the international system retains sufficient institutional capacity to prevent strategic geography from becoming progressively monetised through operational coercion.
The Limits of Institutional Response
One of the clearest lessons emerging from Hormuz is that contemporary maritime governance suffers from a widening asymmetry between legal affirmation and enforcement capability.
The international community possesses extensive mechanisms for restating navigational principles.
It possesses far fewer mechanisms for compelling compliance once strategically important states conclude that gradual operational revision can proceed without intolerable cost.
This is not unique to Hormuz.
Across multiple domains of international order — cyber governance, sanctions regimes, maritime boundaries, outer space, and even multilateral trade systems — institutional frameworks increasingly confront forms of pressure designed not to destroy legal regimes outright, but to erode their practical authority incrementally.
That erosion is often difficult to reverse because it operates below the threshold traditionally associated with overt treaty violation or direct military confrontation.
Maritime law remains among the most successful and durable components of the post-war international legal order.
Yet its durability has always depended upon a broader strategic equilibrium in which major commercial and naval powers continued to perceive navigational openness as collectively beneficial.
The deeper question now emerging is whether that equilibrium itself is beginning to fragment.
If strategic waterways become governed increasingly through persistent coercive ambiguity rather than stable legal consensus, the future of maritime order may depend less upon formal doctrine than upon the resilience of the institutions — commercial, naval, diplomatic, and financial — capable of sustaining practical circulation despite mounting instability.
What to Watch
Three developments will determine whether Hormuz stabilises as a legally governed navigational corridor or consolidates as a permanently contested zone of strategic control.
The first is whether Iranian toll proposals evolve from rhetorical signalling into operational implementation.
Even selective or informal fee collection would carry significance far beyond the immediate revenue question. The central issue is whether coercively generated control over strategic geography can acquire practical legitimacy through commercial accommodation.
The second is the evolution of Omani positioning.
Muscat occupies a uniquely important space within the regional equilibrium. Oman’s diplomatic posture — whether toward active mediation, continued strategic ambiguity, or more formal legal positioning — may prove decisive in determining whether Hormuz remains governable through regional diplomacy rather than permanent militarised confrontation.
The third is the long-term behaviour of insurance and freight markets.
The practical accessibility of Hormuz increasingly depends not only upon naval deployments or treaty interpretation, but upon how global commercial systems price sustained uncertainty. If elevated risk premiums become institutionalised over time, the Strait may remain formally open while becoming functionally constrained.
At that point, the question of whose strait it is legally may matter less than whose risk it has become commercially.
Conclusion: The Future of Navigational Order
The contest unfolding in Hormuz is no longer simply about whether ships possess a legal right of passage.
International maritime law already answers that question.
The deeper issue is whether contemporary maritime order possesses the institutional capacity to preserve practical navigability once strategic risk itself becomes a tool of governance.
The law of transit passage guarantees a formal right of movement. It does not guarantee the commercial, logistical, insurance, and security conditions necessary for that movement to remain economically viable.
That distinction may increasingly define the future of maritime order in the twenty-first century.
The struggle over Hormuz is therefore not simply about Iran, nor solely about the Gulf.
It is about whether openness within strategically contested spaces can still be sustained once operational coercion begins to outpace the institutions designed to constrain it.
And it is about whether international law, confronted by persistent strategic pressure, remains capable of governing the circulation systems upon which the global order itself depends.
FURTHER READING
ACADEMIC & SCHOLARLY
The International Law of the Sea — Donald Rothwell and Tim Stephens
The definitive contemporary treatment of the law of the sea, covering UNCLOS and its interpretation across all major domains including straits, transit passage, and the legal architecture of navigational rights.
The Oxford Handbook of the Law of the Sea — Rothwell, Oude Elferink, Scott and Stephens
A comprehensive scholarly reference across all aspects of UNCLOS and customary maritime law, essential for understanding the legal framework within which the Hormuz dispute operates.
PRIMARY SOURCES
UNCLOS Part III: Straits Used for International Navigation
The foundational treaty text establishing the transit passage regime. Articles 34–45 set out the legal framework at the heart of the Hormuz dispute.
Corfu Channel Case (ICJ, 1949)
The foundational International Court of Justice ruling establishing that states may not use international straits to exercise sovereignty or deny passage. The epigraph of this issue is drawn directly from the Court's judgment.
LITERARY & GENERAL NONFICTION
The Prize — Daniel Yergin
The definitive history of the global oil industry and its relationship to geopolitical power. Essential background for understanding why the Strait of Hormuz carries such concentrated strategic significance and why its governance has been contested for decades.
The Box — Marc Levinson
A history of containerisation and global supply chains that illuminates how deeply integrated modern commerce depends upon the predictable and uninterrupted circulation of goods through maritime chokepoints.
The Revenge of Geography — Robert D. Kaplan
A contemporary treatment of how geography shapes political and strategic outcomes, with direct relevance to the strategic logic underpinning the Hormuz confrontation.
GLOBAL SOUTH PERSPECTIVES
International Law and World Order — B. S. Chimni
A rigorous TWAIL critique of how international legal regimes embed structural asymmetries — directly relevant to understanding how 'navigational freedom' has historically functioned as a doctrine serving dominant maritime powers.