Weaponising Hormuz: How Iran’s coercive leverage collides with global energy, legal limits

Iran can impose major costs on shipping through the Strait of Hormuz, but it cannot sustainably “own” or permanently close the waterway without accelerating diplomatic isolation, military risk and economic damage to itself.

The world gets it: Iran has proven its coercive maritime leverage over the narrow strait by virtue of its geography and military assets.

The regime in Tehran can disrupt passage of commercial vessels, raise insurance and freight costs, and force energy consumers into crisis management — but it cannot replace the international legal principle of freedom of navigation with any durable Iranian toll regime.

The immediate situation is serious. UK Maritime Trade Operations has confirmed incidents involving commercial vessels struck by "unknown projectiles" or drones.

UKMTO advised ships to exercise heightened caution and report suspicious activity.

The UAE has publicly attributed attacks on ADNOC-linked vessels to Iran and called the use of Hormuz as a tool of economic coercion “piracy,” prompting Abu Dhabi to suspend all trade and financial transactions with Iran until further notice.

The reported campaign by Iran has already caused traffic through the strait to slow sharply.

The disruption has global consequences.

Before the crisis, roughly 20 million barrels per day moved through Hormuz; flows fell to an average of 2.7 million bpd in March through May, according to the International Energy Agency.

That is a loss on a scale no single rerouting system can fully absorb, as per the International Energy Agency (IEA).

Iran’s leverage comes from geography. Its coastline, islands, missiles, drones, naval forces and proxy relationships allow it to threaten ships transiting a narrow passage.

The aim is often not to stop every tanker.

It is to create enough risk that owners, insurers, charterers and crews alter behaviour — slowing traffic, demanding security guarantees, charging higher premiums or declining voyages altogether.

A full or prolonged closure, however, would impose heavy costs on Iran as well:

Iran can, therefore, create a persistent threat environment, but it cannot turn that into legitimate sovereignty over an international strait.

International law protects transit passage through straits used for international navigation; coercive attacks on commercial vessels are not a lawful bargaining tool.

Iran cannot hold Hormuz hostage indefinitely — though it has so far proven an ability to make the cost of reopening it extremely high.

To report that only the United States and Gulf states having objected to Iran's threats and attacks on commercial ships in Hormuz is incomplete.

Egypt, Japan, Western and G7 Powers, regional and Middle Eastern nations and the Arab League have condemned attacks on commercial shipping and called for action to protect navigation.

China has repeatedly urged the reopening and safe navigation of the Strait of Hormuz. Beijing stresses that keeping the vital energy chokepoint "open" is essential for global trade and serves the mutual interests of the international community.

The UN Security Council has also expressed concern over escalating regional attacks on merchant shipping and affirmed the importance of freedom of navigation, although consensus on assigning blame or imposing consequences remains politically difficult, according to the UN.

The problem is less a lack of condemnation than an enforcement gap. Many governments oppose attacks on civilian shipping but are reluctant to become parties to a US-Iran confrontation.

China and other major Asian importers have a strong material interest in restoring Hormuz traffic, yet may prefer private pressure, commercial adaptation and diplomacy over public alignment with Washington.

That ambiguity itself plays into Iran’s strategy: keep pressure below the threshold that produces a unified international military response, while still making normal shipping prohibitively risky.

That low-pressure strategy may not last long.

Now, the Trump administration has made the equation over the Iran regime clearer for the rest of the world: "If you're not with us, you're against us".

Washington on Wednesday shifted tactics, pressing its allies — and China — to fall in line behind President Donald Trump’s economic war on Iran. The move signals a broader effort to turn sanctions into a coordinated international squeeze on the Tehran regime, rather than relying on US measures alone.

The pressure comes as Washington seeks to choke off Iran’s access to trade, oil revenues and financial networks, raising the stakes for countries that continue doing business with Tehran.

For China, a major buyer of Iranian oil, the demand puts Beijing in a difficult position between its economic interests and the escalating US campaign.

There is no single “exact” global number because databases count vessel types differently — for example, whether they include product tankers, chemical tankers, LNG carriers, small coastal vessels, inactive ships or sanction-linked “shadow fleet” vessels.

There were about 116,000 vessels of at least 100 gross tonnes at the start of 2026, based on International Maritime Organisation (IMO) data.

Pre-war Hormuz traffic was about 144 vessels a day (as of mid-2025) of which 37% were tankers.

The 8,445 figure is the clearest published count for crude-oil tankers, while a lower US Congressional Research Service (CRS) figure reflects a narrower classification.

IMO’s GISIS database is the authoritative ship-identification registry, but it is a live vessel-by-vessel database rather than a single regularly published global tanker tally.

Here's the point: the world has thousands of tankers, but not thousands that can instantly replace Gulf volumes.

Tankers are specialised by size, cargo and route; a disruption traps vessels, lengthens voyages and removes effective carrying capacity from the market.

While the world cannot pretend Hormuz no longer matters, the global response has so far focused on buying time and reducing dependence.

The most likely end-state is not permanent Iranian control of Hormuz and not a clean military solution. It is a negotiated reopening backed by monitoring, deterrence and security understandings that allow all sides to claim "partial" success.

Iran regime’s practical objectives may include survival, compelling direct talks with Washington, extracting sanctions or security concessions, demonstrating that its regional interests cannot be ignored, and raising the cost of military pressure.

The US and its partners seek the opposite outcome: unimpeded navigation without conceding that Iran has a veto over an international waterway.

The IEA has earlier reported that a recent US-Iran agreement was intended to restore regular traffic, with some exports beginning to rise. The subsequent reported attacks on commercial shipping and warnings show that an agreement on paper is not yet the same as dependable freedom of navigation at sea.

The strategic lesson is stark: Iran can weaponise Hormuz, but each use of that weapon strengthens the long-term case for pipelines, stockpiles, alternative suppliers, diversified Asian energy sourcing and international maritime-security cooperation.

Its leverage is potent precisely because Hormuz matters so much — and it diminishes if the world succeeds in making the strait less irreplaceable.