31MAY

Iran: only allied ships may pass Hormuz

2 min read

09:14UTC

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ConflictDeveloping

Iran's UN representative Ali Mousavi told the International Maritime Organisation this week that vessels belonging to or linked to 'aggressor parties' forfeit the right of innocent passage through the strait of Hormuz. ¹ PressTV, Iran's official state broadcaster, confirmed the statement as Iran's official legal position. Permitted countries under the vetting system are India, China, Russia, Iraq, and Pakistan.

The IMO statement is the formal legal scaffolding for the parliamentary toll bill being drafted simultaneously. Iran is constructing a two-layer legal architecture: domestic statute (the Majlis bill) combined with formal international notification (the IMO submission) that pre-empts claims that Iran is acting without legal notice. The IMO notification mirrors Egypt's communication to the Suez Canal Users Association in 1956 after nationalisation.

Trump had claimed Iran offered Hormuz concessions , and Pakistan confirmed the 15-point US proposal . The IMO statement directly contradicts the framing that Iran is moving toward reopening the strait: Iran is doing the opposite, establishing formal legal grounds for continued selective passage that would survive any ceasefire under the pending domestic legislation. Pentagon planning for a Kharg Island assault continues ; the IMO statement is Iran's legal counter-move to that planning, establishing that any forcible passage would constitute a violation of Iran's defined legal framework rather than merely a military confrontation.

Deep Analysis

In plain English

Iran told the international shipping authority that ships linked to countries attacking it lose the right to pass through the Strait of Hormuz freely. This would let Iran legally charge or block ships from the US, Israel, and their allies. International law says countries cannot block international waterways, but Iran argues it is defending itself.

Deep Analysis

Root Causes

Iran is exploiting a gap in UNCLOS: the convention assumes coastal states will not be at war with the states whose vessels transit their waters. The legal framework was not designed for a scenario where a coastal state is under active military attack.

By framing the toll as a defensive measure rather than an offensive blockade, Iran creates legal ambiguity that is harder to challenge than a straightforward closure.

Source Landscape

This story draws on mixed-leaning sources from Israel

Israel

Primary parallel: Libya declared the Gulf of Sidra a closed bay in 1973, claiming sovereignty over international waters. The US challenged Libya's claim with naval exercises in 1981 and 1986, leading to military confrontations. Libya's legal position was never accepted by any international court.

Counter-parallel: Iran's position is stronger than Libya's: Iran actually controls three sides of the strait of Hormuz, and the toll system is generating revenue and operating in practice. Libya never achieved physical control over the Gulf of Sidra.

Consensus view: The International Maritime Organisation's Legal Committee and UNCLOS scholars assess that the right of innocent passage through international straits cannot be unilaterally revoked by a coastal state. Iran's claim has no precedent in modern maritime law.

Counter-view: Iran argues that UNCLOS Article 25 permits a coastal state to take necessary steps to prevent passage that is not innocent. Tehran frames the toll system as a defensive measure against states conducting military operations against it, which it argues terminates those states' right to innocent passage.

Key tension: Whether Iran's legal argument has enough ambiguity under UNCLOS to survive challenge, or whether it constitutes a unilateral rewrite of international maritime law.

Sources:Times of Israel / CENTCOM·Times of Israel / CENTCOM

Mentions:Kharg Island →

First Reported In

Update #49 · Hormuz toll into law; Tangsiri killed

Times of Israel / CENTCOM· 27 Mar 2026

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Causes and effects

Caused by

Pentagon plans to seize Kharg Island

Legal notification to IMO constructs formal basis for resisting forcible passage by US forces

Occurred 24 Mar 2026

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Trump claims Hormuz prize; Iran silent

IMO statement directly contradicts Trump's claim that Iran is offering Hormuz concessions

Occurred 24 Mar 2026

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This Event

Iran: only allied ships may pass Hormuz

Led to

Iran's five peace terms: Hormuz first

Iran's IMO notification revoking innocent passage for hostile parties is the international legal layer underpinning the five conditions, with Hormuz sovereignty as condition five.

Occurred 25 Mar 2026

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One ship through Hormuz in 24 hours

Iran's IMO legal notification on Hormuz sovereignty builds the international-law layer of the dual-architecture strategy reinforcing the de facto closure.

Occurred 29 Mar 2026

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Different Perspectives

Iran human rights monitors (Amnesty International, Iran HRM, Hengaw)

Monitors documented 30 women held on capital moharebeh charges in a basement prison ward, Benyamin Naqdi's death sentence with a forced-confession broadcast, and 39 political executions since February. Iran's security courts have processed protest cases at uninterrupted wartime tempo regardless of the diplomatic track.

Lloyd's of London (war-risk underwriters)

Lloyd's held its Hormuz war-risk designation at $10-14 million per voyage while Brent fell 19%, maintaining a structural divergence from futures pricing. Underwriters require a UN Security Council resolution or government certification letter, not diplomatic optimism, before de-listing the strait.

Oman (Sultan Haitham's government)

Muscat issued a mine alert in its own territorial waters while denying any Hormuz toll plan after US Treasury threatened sanctions. A suspected mine in Omani waters on the same weekend as US financial pressure forces Muscat to demonstrate sovereignty without appearing to choose sides.

China (PRC)

Beijing sent scholars rather than its defence minister to Shangri-La for the second year running and addressed Taiwan and multilateralism without mentioning Iran. China maintains its bilateral energy corridor protection with Tehran while refusing the diplomatic exposure of a public position at multilateral forums.

Iran Supreme National Security Council

The SNSC framed the unsigned MOU as a 10-point Iranian victory with enrichment already recognised, and the foreign ministry rejected Trump's nuclear conditions within hours. Tehran treats each unsigned day as validation that Iran has retained its stockpile without surrendering it.

Trump administration (CENTCOM/White House)

Trump posted three non-negotiable public conditions while CENTCOM disabled a commercial ship and Hegseth threatened resumed strikes from Singapore. The administration treats the unsigned MOU as leverage to extract maximum Iranian concessions before any ceasefire instrument is committed to paper.