Would Iran close the Strait of Hormuz?

Friday 30 December 2026

Iran’s periodic threat to close the Strait of Hormuz is designed to sound absolute, yet to operate on a sliding scale. Tehran rarely needs to declare a formal blockade to achieve many of the effects she seeks. In a narrow waterway where the usable shipping lanes are only a few kilometres wide, a blend of live-fire exercises, drone and missile signalling, selective seizures and the mere suggestion of mines can make commercial operators behave as if closure has already begun. 

The reason this works is that Hormuz is less a place than a system of dependencies. In the first months of 2025, the International Energy Agency estimated that roughly 20 million barrels per day of crude oil and oil products transited the strait, about a quarter of global extraction moved by sea, with the bulk destined for Asia. The same factsheet notes that LNG exports from Qatar and the UAE moving through Hormuz represent a material share of global LNG trade, and that bypass options are limited to a few pipelines with only partial spare capacity. 

If Iran were actually to try to close the strait, the most likely geopolitical outcomes would unfold in layers.

First comes market power in its rawest form: risk. Even before physical disruption, insurance premia rise, some owners refuse fixtures, and charterers delay liftings. Prices then respond not only to barrels missing today but to uncertainty about barrels missing tomorrow. That is why analysts and traders react sharply to credible threats of obstruction, and why the political leadership of energy-importing states tends to treat “mere” signalling as a strategic event. 

Secondly comes compulsion diplomacy aimed at the states that matter most to Iran’s export earnings. A prolonged, genuine closure would also constrict Iran’s own ability to export through her Gulf terminals, which is part of the paradox: she can hurt others badly, but she also harms herself. The practical geopolitical consequence is that Tehran’s coercive message is rarely meant for Washington alone. It is aimed at Beijing, New Delhi, Tokyo and Seoul, and at the Gulf monarchies, by forcing them to weigh their economic stability against continued confrontation. 

Thirdly comes naval reality. A closure attempt would almost certainly produce a US-led maritime campaign whose public aim would be freedom of navigation, and whose operational aim would be to make commercial transit possible again, even if only through escorted convoys. The United States Fifth Fleet’s presence, longstanding multinational maritime coordination, and the existence of ad hoc security constructs in and around the strait mean that the initial response would be rapid and multinational, even if the political coalition is narrower than NATO. 

From that point the outcomes diverge according to what “closure” means in practice.

A harassment scenario, which is the likeliest, is not a declared blockade but a period of heightened danger: live-fire drills, electronic interference, selective boardings, and sporadic attacks by proxies elsewhere in the region that raise the perceived risk of Hormuz transits. The geopolitical outcome here is a familiar one: heightened US and allied presence, a rise in tanker earnings, a surge in Gulf security diplomacy, and intensified backchannels in which Iran offers de-escalation in exchange for sanctions relief or concessions on her nuclear file. This scenario strains Western unity less than one might expect because it is still easy to frame as law enforcement against unlawful interference, but it strains Asian unity because Asian importers must decide how hard to press Tehran when they are also dependent upon Gulf supply. 

A short, sharp closure attempt, lasting days rather than weeks, would be more dangerous politically than economically. The damage would be concentrated in credibility. If Iran can demonstrate that she can interrupt flows at will, even briefly, she strengthens deterrence and bargaining power for months afterwards. Conversely if the United States and her partners reopen the corridor quickly (including the immediate use of force), Tehran’s deterrent narrative is punctured, which can tempt escalation elsewhere as she seeks to restore it. The most probable geopolitical outcome is therefore not “closure then reopening”, but a cycle: provocation, countermeasures, partial reopening, then renewed provocation in a different form. This is how chokepoints become theatres rather than incidents.

A sustained closure, lasting weeks, that might accompany a full-scale war between the United States and Iran, is the scenario that changes alignments. The IEA notes that alternative pipeline routes exist but are limited relative to the volumes normally transiting Hormuz, and that a prolonged disruption would generate shortages quickly. In that environment:

• The Gulf monarchies would press Washington for decisive action, yet also fear that decisive action makes their ports and energy infrastructure the primary targets. Their diplomacy would oscillate between urging force and urging restraint, depending on the immediate vulnerability of their own assets.

• China would face a dilemma that she has long tried to postpone. She benefits from stable Gulf flows and has an interest in preventing a US-Iran war, but she has also built a posture of strategic ambiguity in Middle Eastern security. A sustained closure would increase pressure on Beijing to translate commercial leverage into political leverage over Tehran, while also increasing the incentives to accelerate diversification, stockpiling, and non-Gulf supply deals.

• Russia would enjoy windfall revenues from higher prices, yet she would also inherit the strategic drawback that severe price spikes tend to accelerate substitution and investment in alternatives. More immediately a global energy shock would complicate Western fiscal and political support for Ukraine, because publics notice petrol prices and heating bills more readily than distant front lines. That is one reason why Moscow tends to thrive on instability without necessarily controlling it.

• Europe would be less exposed to Gulf oil than some Asian markets, but she would still pay the global price. The political outcome would be renewed European arguments about strategic autonomy, energy resilience, and maritime security burden-sharing with the United States, but with the added constraint that Europe’s naval capacity is finite and already heavily tasked.

Finally, there is the question of escalation thresholds. In a sustained closure scenario, the United States would be drawn towards actions she normally prefers to avoid: strikes against coastal missile batteries, drones, radar and naval assets, and possibly Iranian command nodes associated with harassment operations. Tehran, in turn, would have incentives to widen the battlefield through regional partners, so that the cost of reopening Hormuz is paid not only in the strait but in multiple arenas at once. This is why many observers expect both sides to calibrate towards intense signalling and controlled violence rather than an outright, prolonged blockade. 

The most likely geopolitical outcome, then, is not a cinematic “closing” of Hormuz, followed by a heroic “opening”, but a dirty period of partial denial: enough danger to frighten markets and bend diplomacy, not enough to force Iran into a war she cannot afford or the United States into a regional campaign she does not wish to fight. Tehran threatens closure because the threat itself already redistributes money and attention. Washington signals force because signalling itself can sometimes keep the threat in the realm of theatre. The rest of the world, especially Asia’s import-dependent economies, becomes the unwilling audience that pays for the performance.