5JUN

IRGC Navy writes its own Hormuz transit rulebook

3 min read

08:43UTC

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.

← Back to Hezbollah veto stalls Iran-US deal Jump to analysis ↓

ConflictDeveloping

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

Read original →

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

Read story →

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

Read story →

Different Perspectives

Israel

IDF Chief Eyal Zamir declared on 3 June there was no ceasefire for his forces, and strikes killed at least 10 civilians and one Israeli soldier on 4 June. The IDF killed Hezbollah's chief engineer and warned three south Lebanon villages to evacuate on 5 June, advancing into ground the unsigned Washington framework has not caught.

Hezbollah / Lebanon

Naim Qassem rejected the Washington Lebanon framework on 4 June as "absurd, humiliating and insulting", blocking a ceasefire instrument that required Hezbollah to withdraw north of the Litani before any Israeli withdrawal. Over one million Lebanese remain displaced; the framework's collapse prolongs that toll.

Iran

Foreign Minister Araghchi publicly coupled the Lebanon ceasefire to the Iran-US nuclear track on 4 June, carrying IRGC authority rather than his own civilian mandate. The IRGC delegation has sent no HEU counter-proposal since Araghchi confirmed no progress that same day; Mojtaba Khamenei's 21 May order to keep the 440.9 kg stockpile inside Iran remains operative.

United States

Rubio placed the Iran-US deal at 95 per cent complete on 4 June while the administration signed no Iran instrument and OFAC designated only Cuban targets. Trump separately disclosed and rejected an airlift plan to collect Iran's HEU stockpile, claiming the material is "entombed", a claim the IAEA cannot verify.

China

Beijing's MOFCOM Blocking Rules constrain OFAC enforcement on the mainland; China has not corroborated Trump's verbal account of any bilateral summit, and the rial's failure to hold its Rubio bounce, combined with the IRGC's stablecoin rail closure, increases Chinese yuan-denominated oil-payment exposure through Hormuz.

Bahrain

The IRGC struck Bahrain on 3 June as its sirens sounded and its PAC-3 magazine neared exhaustion; excluded from Rubio's 2 May emergency resupply, Bahrain received a 50-round Federal Register notice on 1 June on an 18-month delivery timeline, meaning it is defending the US Fifth Fleet headquarters on the last rounds it has.