MADRID – Four weeks into the U.S and Israeli offensive against Iran, the centre of gravity has shifted from contested airspace to a narrow maritime corridor less than 30 kilometres wide. The Strait of Hormuz, long treated by Western planners as an artery requiring permanent openness, remains physically navigable. It has not been closed. What has changed is the condition under which passage occurs.

Iranian Armed Forces has not imposed a blockade. It has instead transformed the strait into a controlled passage system, where transit depends on prior clearance. The waterway functions less as an open corridor than as a regulated gate, with selective access, screening procedures and informal fees.

This distinction is not rhetorical. It captures the central strategic development of the conflict. Iran has not denied circulation outright; it has reshaped the terms on which it takes place. In doing so, it has exposed a structural tension: the separation between military superiority and the ability to guarantee movement, a foundational assumption of the global economy.

The infrastructure of control

Geography defines the operating environment. At its narrowest point, deep-water channels run closer to Iran’s coast than to the Arabian Peninsula. For decades, the presence of the U.S. Fifth Fleet was assumed to provide sufficient deterrence. That assumption no longer holds. From positions along its coastline and from islands such as Qeshm and Larak, Iran has deployed a dispersed system of surveillance and disruption: drones tracking vessel movements, fast craft shadowing tankers, and intermittent signals of mines or missile capability. There is no continuous interdiction. The effect is cumulative uncertainty.

The operational process has become increasingly clear. Tanker operators engage intermediaries linked to the IRGC. They provide documentation: ownership structures, flag registration, cargo details, destination, crew lists and AIS data. These are reviewed against defined criteria, including the absence of U.S. or Israeli links. Where approval is granted, a payment is reportedly agreed. Transactions are conducted in cash, Chinese yuan or USDT via the Tron network. Clearance is then issued via VHF radio, specifying timing and routing through Iranian territorial waters, typically near Larak Island, where visual verification may occur. Transit follows without escort. Security derives from exemption, not protection.

Traffic volumes have fallen sharply, by an estimated 70 to 80 per cent. The vessels that continue to transit do so under IRGC clearance. This reflects a long-developed form of littoral strategy, where proximity compensates for conventional asymmetry. Iran does not challenge control of open seas; it concentrates on constraining a chokepoint. The result is not disruption through force, but through altered expectations. Shipping depends on predictability. Once uncertainty becomes structural, activity contracts.

This dynamic is best understood in the context of the Persian Gulf’s historical infrastructure. Maritime routes, ports and pipelines were developed under imperial frameworks — first British, then American — designed to channel hydrocarbons into global markets while minimising local political interference. Ports such as Jebel Ali and Ras Tanura were integrated into a dollar-based system supported by naval power and labour hierarchies. The concept of the “global commons” masked the extent to which access was always contingent on external control.

Iran’s intervention operates at the level of risk rather than territory. By destabilising predictability, it has altered the relationship between force and economic effect. This is a form of counter-logistics: disruption deployed to expose the fragility of systems assumed to be stable. Mines, drones and calibrated signalling operate below the threshold of direct confrontation. Their function is not to defeat U.S. naval forces, but to make their presence insufficient to ensure full passage.

Insurance markets have become the decisive mechanism through which this shift is expressed. Major underwriters, including those associated with Lloyd’s, have withdrawn standard coverage for Hormuz transits. War-risk premiums have increased significantly, in some cases reaching levels that undermine commercial viability. Crucially, risk models now incorporate IRGC clearance as a mitigating factor. Vessels able to demonstrate compliance are assessed as lower risk than those that cannot.

This introduces a structural consequence. Insurance availability becomes conditional on engagement with Iranian authority. Vessels without clearance are effectively immobilised, not by direct interdiction but by the absence of financial cover. The insurance market, without explicit coordination, has operationalised a system in which access to the strait is mediated through Iran.

The unravelling of an order

For decades, the U.S. approached the Strait of Hormuz as an open transit zone controlled through naval dominance. This arrangement depended on the absence of credible disruption. That condition no longer applies. Iran has not replaced the existing order, but it has revealed its underlying dependencies.

The U.S. response has highlighted the limits of a strategy centred on military force. Carrier groups remain deployed and air operations continue. Yet the primary objective — restoring predictable transit — has not been achieved. Attempts to organise multinational escort operations have stalled. European participation remains limited. Persian Gulf states, despite economic exposure, are cautious about escalation. China, as a major importer of Persian Gulf energy, has little incentive to support arrangements that could complicate its relations with Tehran. The result is fragmentation rather than coordinated action.

Policy signals from Washington reflect this uncertainty. Calls for escalation coexist with measures aimed at mitigating domestic economic impact, including discussions of strategic reserve releases. The inconsistency reflects a broader difficulty: restoring full circulation requires more than suppressing threats. It depends on rebuilding confidence among commercial actors, a process beyond the reach of military tools alone.

Iran operates within constraints but has demonstrated an ability to convert them into leverage. Its exports have declined but continue through alternative channels. Higher prices and intermediary networks offset part of the loss. More importantly, the disruption reinforces Iran’s centrality to regional stability. Attempts to exclude it impose costs on the wider system.

This reflects the historical construction of Persian Gulf logistics. Shipping routes and security arrangements were shaped to facilitate outward flows of energy within a framework of external control. The designation of these waters as a global commons obscured their managed character. Iran’s actions do not dismantle this system, but they interrupt its operation and reintroduce political contestation into a space previously stabilised by force and finance.

What is emerging is not a breakdown of order, but its reshaping. The assumption that circulation depends on a single external guarantor is giving way to a more regionally anchored logic of control. Power is no longer organised around distant naval dominance, but around the capacity to structure the material and financial conditions through which flows are sustained.

At the centre of this reshaped order, Iran is positioned as the nodal point. Its geographic location, combined with its ability to intervene in the Strait of Hormuz, allows it to exert influence not by closing routes, but by governing their viability. This does not amount to hegemony in the classical territorial sense, but it approaches a functional equivalent: the ability to condition access to critical infrastructures on which global circulation depends.

Engagement with China and Russia reinforces this position. These relationships do more than offset Western pressure; they embed Iran within a wider Eurasian framework in which connectivity, rather than isolation, defines strategic relevance. Corridors linking the Indian Ocean to continental supply chains deepen this integration, gradually transforming Iran from an object of containment into a central reference point within emerging patterns of trade and energy distribution.

At the level of perception, the implications are equally significant. The longstanding image of an open Persian Gulf, controlled by American power and embedded in a stable global market, no longer holds as an unquestioned baseline. Circulation persists, but under conditions that are increasingly contingent, negotiated, and shaped by Iran’s capacity to modulate risk. What was once treated as a neutral space of transit is now visibly structured by political authority.

Iran’s approach illustrates a form of power exercised through the governance of flows rather than their outright denial. By introducing calibrated uncertainty into a system dependent on predictability, it has redefined the relationship between military capability and economic effect. The objective is not closure, but conditionality: to ensure that movement occurs on terms it can influence and, when necessary, enforce.

For the United States, the implications extend beyond the immediate conflict. Military superiority remains decisive in bounded engagements yet proves insufficient to secure the infrastructural and financial architectures that underpin global circulation. Where those architectures can be unsettled, authority becomes less concentrated and more subject to negotiation.

The Strait of Hormuz, long framed as a point of vulnerability, now functions as a locus of strategic leverage. Geography, infrastructure and doctrine converge in ways that allow Iran to exert sustained influence over a system built on assumptions of uninterrupted flow. Iran has not overturned that system. It has demonstrated that its continuity now depends, in part, on its position at this critical node.