Skip to content
Briefings are running a touch slower this week while we rebuild the foundations.See roadmap
Iran Conflict 2026
4JUN

IRGC fires on two Indian tankers after clearance

3 min read
11:25UTC

IRGC gunboats opened fire on the Sanmar Herald and Jag Arnav in the Strait of Hormuz on 18 April after Iranian authorities had granted both vessels prior radio clearance to transit.

ConflictDeveloping
Key takeaway

Radio clearance from Iranian authorities now carries no insurable protection value for Hormuz-bound shipping.

Islamic Revolutionary Guard Corps (IRGC) gunboats fired on the Indian-flagged very large crude carrier Sanmar Herald and the tanker Jag Arnav in the strait of Hormuz on 18 April, after both vessels received prior radio clearance from Iranian authorities to transit 1. No warning preceded the fire. Both ships reversed course back through the strait.

An intercepted bridge transmission captured one crew's response in a single radio line: "You gave me permission to go... you are firing now!" 2. The IRGC is Iran's ideological parallel military force, commanding proxy networks, domestic security and Hormuz naval operations alongside the conventional armed forces; gunboat encounters with commercial shipping in the strait are its signature. the strait of Hormuz is the 33-kilometre maritime chokepoint through which roughly a fifth of global seaborne oil passes.

The pattern repeats an earlier fire. On 17 April, Iran's joint military command declared Hormuz reopened for 24 hours, and the IRGC fired on an Indian-flagged vessel the same day after granting clearance . Iran reversed the opening on 18 April, declaring the strait "returned to its previous state under strict management and control", and the Sanmar Herald and Jag Arnav attacks followed inside hours.

For shipping insurers, the IRGC's grant-and-fire sequence prices Iranian radio clearance at zero protection value. Underwriters had been pricing a carve-out in which vessels carrying Iranian permission could transit safely; two incidents inside 24 hours, both on Indian hulls, both preceded by clearance, remove that assumption. The question that replaces it is whether any transit through Hormuz now carries insurable status while IRGC targeting decisions are made at gunboat level rather than by Tehran's foreign ministry.

Deep Analysis

In plain English

Imagine a toll booth operator waves you through, then a guard 100 metres down the road opens fire on your car. That is what happened to two Indian tanker ships in the Strait of Hormuz on 18 April. The Strait of Hormuz is a narrow waterway ; only 33 kilometres wide at its tightest ; between Iran and Oman. About 20% of the world's oil used to pass through it every day before this conflict started. Iranian military forces called the Islamic Revolutionary Guard Corps (IRGC) now control who goes through. On 18 April, two Indian oil tankers ; the Sanmar Herald and the Jag Arnav ; received radio permission from Iranian authorities to transit. Then IRGC gunboats fired on them anyway. A recorded transmission from the Sanmar Herald's bridge crew captured the crew's shock: 'You gave me permission to go... you are firing now!' Both the Sanmar Herald and the Jag Arnav reversed course and retreated. This matters because it shows Iran can deny passage even after granting radio clearance; the IRGC has done this on two consecutive days.

Deep Analysis
Root Causes

Iran's 1982 domestic maritime law, updated in 2024, claims jurisdiction over 'hostile-linked vessels' transiting Hormuz ; a category defined broadly enough to cover any flag state that has sanctioned Iran. India has not formally sanctioned Iran, but its state refiners were the primary buyers of GL-U-covered cargoes.

IRGC naval doctrine under the Decentralised Mosaic Defence delegates launch authority to 31 autonomous provincial units; the disconnect between the radio operator granting clearance and the gunboat commander firing suggests the two functions may sit in separate command chains.

The broader structural root is Iran's contested legal position at Hormuz: Tehran has never ratified the UN Convention on the Law of the Sea (UNCLOS), which grants transit passage through international straits. By operating outside UNCLOS, Iran can claim domestic maritime law governs passage terms ; meaning clearance granted under Iranian domestic procedures can be revoked under the same domestic authority without reference to international law.

Escalation

The grant-and-fire pattern across two consecutive days (17 April on one vessel, 18 April on two) suggests an emerging tactical norm rather than isolated incidents. It converts Indian tankers ; previously partially protected by India's non-aligned status and direct India-Iran diplomatic engagement ; into targets, widening the range of nations directly confronting Iran's Hormuz interdiction.

What could happen next?
  • Risk

    India's diplomatic protest creates pressure on New Delhi to join multilateral Hormuz escort arrangements ; a step that would convert India from non-aligned observer to active participant in the maritime confrontation.

    Short term · 0.72
  • Consequence

    The clearance-then-fire pattern voids the value of direct India-Iran diplomatic channel as a vessel-protection mechanism, which had functioned since March 2026 (ID:1060).

    Immediate · 0.82
  • Precedent

    Firing on vessels after issuing radio clearance sets a documented pattern that European navies drafting Hormuz rules of engagement at Northwood must account for ; any escort mission assumes clearance means something.

    Medium term · 0.78
First Reported In

Update #73 · Russia yes, Iran no: Treasury signs only one waiver

CBS News· 19 Apr 2026
Read original
Different Perspectives
China
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.
Israel
Israel
IDF Chief Zamir said on 3 June there is no ceasefire for his forces even as Israel signed the Washington Lebanon framework requiring Hezbollah withdrawal south of the Litani; a UNIFIL peacekeeper was killed by mortar near Marjayoun on the same day, exposing the gap between the diplomatic framework and a ground advance that has not stopped.
Bahrain
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.
Qatar
Qatar
Qatar offered $6bn under OFAC Licence L-2 restrictions and sent Ghalibaf's delegation home empty-handed; the $6bn ceiling is a legal constraint, not a negotiating floor, and Rubio's no-sanctions-relief testimony means Qatar cannot revise it without White House action that has not been requested.
Kuwait
Kuwait
Kuwait expelled two Iranian diplomats within 24 hours of the airport strike, the strongest and fastest Kuwaiti diplomatic move of the conflict, while keeping the full mission in place to preserve a communication channel; it has now invoked Article 51 self-defence, filed a formal protest, and expelled diplomats, exhausting its formal toolkit short of full rupture.
United States
United States
Trump narrated a weekend deal while the channel Rubio described under oath, Khamenei's written-only couriers with a 3-to-5-day lag, cannot answer at that speed; CENTCOM called the airport strike deliberate, calculated and unjustified. The House 215-208 vote gave Congress its first on-record war-powers position against the deployment Trump has run without a signed instrument for 96 days.