8JUN

IRGC Navy writes its own Hormuz transit rulebook

3 min read

09:58UTC

Iran's Revolutionary Guard wrote its own transit rulebook for the Strait of Hormuz in the IRGC-aligned Farsi outlet Tabnak. The foreign ministry had no seat at the drafting.

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Key takeaway

Iran's Revolutionary Guard wrote the Hormuz transit rules itself, and its own foreign ministry's clearances no longer hold.

On 17 April the IRGC Navy (Islamic Revolutionary Guard Corps Navy, Iran's parallel naval force) published a formal four-condition order for the Strait of Hormuz in the IRGC-aligned Farsi outlet Tabnak ¹. Non-military vessels may transit only by Iran-designated routes; military vessels are barred; every passage requires prior Guard Corps authorisation; the framework is tied to the Lebanon ceasefire holding.

The Tabnak publication lets Iran's military write over its diplomats in public. Two days later Foreign Minister Abbas Araghchi announced a civilian corridor opening, and the announcement lasted less than 24 hours. Despite the radio clearances Iran's own foreign ministry issued, the Guard Corps fired on the Indian-flagged Sanmar Herald and Jag Arnav on Saturday 18 April . A Sanmar Herald crew member was recorded on open channel saying Iran had cleared the vessel and was now firing on it anyway, which is the evidence the Tabnak order is load-bearing and the foreign ministry's clearances are not.

For shipowners routing hulls through the strait, the practical question is whose paper to obey. The rulebook the IRGC has now published is domestic Iranian doctrine with no signatory outside the Guard Corps. The 1968 Traffic Separation Scheme agreed between Iran, Oman and the IMO has governed Hormuz movement for 58 years, and Iran's own civilian foreign ministry is still a party to it. A counter-view from sympathetic commentators in Tehran is that the Tabnak order is a wartime clarification rather than a substitute for civilian law, and that a single ceasefire can fold it back. That reading is hard to sustain while the Guard Corps is firing on vessels the foreign ministry has cleared.

Deep Analysis

In plain English

Iran has two different armed forces: the regular military and the Islamic Revolutionary Guard Corps (IRGC), which is a separate, more ideologically driven force that reports to the Supreme Leader. On 17 April the IRGC Navy (its sea-going branch) published a set of four rules saying that no ship could cross the Strait of Hormuz without its personal permission, that military ships were banned entirely, and that the rules were tied to the Lebanon ceasefire holding. On 19 April Abbas Araghchi, Iran's Foreign Minister, separately announced the strait was open. Those two announcements directly contradict each other, and they came from two different parts of the same government. When Indian ships tried to follow the foreign minister's clearance, the IRGC fired on them anyway. The IRGC's written order, published two days earlier, turned out to be the one that governed the strait.

Deep Analysis

Root Causes

Iran never ratified the 1982 UN Convention on the Law of the Sea (UNCLOS), which grants transit passage rights through international straits. Tehran's domestic maritime law, updated in 2024, claims jurisdiction over 'hostile-linked vessels', a category broad enough to encompass any flag state that has sanctioned Iran.

The Tabnak four-condition order operationalises that domestic legal claim as a Guard Corps enforcement mechanism, creating a parallel legal architecture Iran can enforce without reference to international maritime law.

The IRGC Navy's institutional position since 2019 has been that Strait of Hormuz access is a tool of statecraft, not a neutral right. The Guard Corps has treated clearance authority as its own operational property through three rounds of tanker harassment. Araghchi's Friday corridor announcement conceded that institutional property without Guard Corps agreement, producing the split the Tabnak order makes legible.

What could happen next?

Precedent
The Tabnak order establishes IRGC written doctrine as the operative transit framework, creating a model for future enforcement that bypasses Iran's civilian foreign policy machinery.
Risk
Northwood planners drafting rules of engagement this week must write against a published adversary doctrine rather than a diplomatic silence, narrowing the range of enforceable coalition positions.

Source Landscape

This story draws on neutral-leaning sources

Primary parallel: In 1987-1988, Iran's Pasdaran naval units operated under Revolutionary Guard command authority that diverged from the regular navy's rules of engagement, producing the tanker attacks that triggered Operation Praying Mantis. The institutional structure (a parallel naval force writing its own doctrine separately from civilian foreign policy) is identical to what the Tabnak order documents in 2026.

Counter-parallel: The 2019 IRGC seizure of the Stena Impero was authorised through Iran's civilian judiciary as a legal response to Gibraltar detaining the Adrian Darya, demonstrating that Guard Corps naval action can run through, rather than against, civilian channels when Tehran chooses to coordinate. The Tabnak order's pre-dating of the Araghchi corridor by 48 hours suggests no such coordination this time.

Consensus view: The International Institute for Strategic Studies (IISS) reads the Tabnak publication as a deliberate command-authority claim: by writing the four-condition order before Araghchi's civilian corridor, the IRGC Navy established primacy in writing, then enforced it in fact when it fired on the Sanmar Herald . The Tabnak document is a retroactive paper trail for an authority the Guard Corps has exercised informally since 2019.

Counter-view: Former Iranian negotiator Hossein Mousavian, writing from Princeton's Program on Science and Global Security, argues the Araghchi-IRGC split is a structured bargaining posture: the civilian corridor creates international goodwill, the IRGC order provides a mechanism to revoke it, and the combination gives Tehran maximum leverage going into ceasefire renewal. Mousavian reads the Sanmar Herald firing as calibrated signalling, not institutional breakdown.

Key tension: Whether the Tabnak order reflects a genuine fracture in Iranian command authority or a choreographed good-cop/bad-cop mechanism that both factions have agreed on privately.

First Reported In

Update #74 · Two unsigned rulebooks collide at Hormuz

Tabnak· 20 Apr 2026

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Causes and effects

Caused by

Hormuz opens then closes in 24 hours

The IRGC Navy's 17 April Tabnak transit order provided the written doctrine that retroactively explained the IRGC firing on Indian tankers that had radio clearance (ID:2578).

Occurred 17 Apr 2026

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This Event

IRGC Navy writes its own Hormuz transit rulebook

Iran now has a civilian enforcement track and a parallel military one, and the military one is the document tankers hit first in open water. A clearance from Iran's foreign ministry buys nothing the Guard Corps has not signed off.

Led to

IRGC boards three ships inside Hormuz

The IRGC Tabnak four-condition transit order established the pattern of kinetic responses to verbal de-escalation, culminating in the 22 April seizures.

Occurred 22 Apr 2026

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Different Perspectives

Bahrain / Gulf partners

Bahrain's PAC-3 interceptor magazine sits at 87% depletion after absorbing IRGC salvos aimed at US bases; no resupply is scheduled before 2027, concentrating the intercept burden on US assets and Israeli Iron Dome and Arrow-3.

IAEA / Vienna process

IAEA officials cited proliferation concerns over 440.9 kg of HEU unaccounted for after 97 days without inspector access; the Board session that opened 8 June cannot retroactively close the evidentiary gap its own resolution documents.

China

China absorbed the Shanghai Qianye designation by OFAC and opposes censure at the IAEA Board, arguing the verification gap was created by strikes rather than Iranian non-compliance, a framing it shares with Russia to protect the non-Western bloc's Board votes.

Russia

Putin reaffirmed at SPIEF on 6 June his offer to hold Iran's uranium stockpile as custodian, a proposal the IAEA's 97-day verification gap now renders undeliverable: no one can transfer or confirm a stockpile that has not been inspected.

United States / Trump administration

Trump publicly asked Netanyahu not to retaliate and described a deal as 95% done; Rubio then acknowledged enrichment terms could take months. The 24-hour gap between the request and the Mahshahr strike removes the credible-restraint argument from US diplomatic leverage with Tehran.

Israel / Netanyahu government

Netanyahu struck the Mahshahr complex and missile sites inside Iran within 24 hours of Trump's public no-retaliation request, a second kinetic override of US counsel that confirms Israel will not allow Tehran to dictate the terms of the exchange.