Iran warns ships not to bypass its chosen Hormuz route

Iran's Islamic Revolutionary Guard Corps (IRGC) Navy has warned commercial vessels that the only authorised transit routes through the Strait of Hormuz are t...

What Happened

Iran's Islamic Revolutionary Guard Corps (IRGC) Navy has warned commercial vessels that the only authorised transit routes through the Strait of Hormuz are those designated by the Islamic Republic of Iran, and that ships must maintain radio contact with the IRGC Navy while transiting.
The warning followed Oman's announcement of a new shipping corridor along the Omani coast, coordinated with the International Maritime Organization (IMO), after decades of vessels preferring the Iranian-coastal corridor designated by Tehran.
Dozens of commercial vessels have transited the Omani-side route, defying Iran's insistence; Iran has characterised transiting without its approval as "unacceptable and dangerous."
A cargo ship was struck approximately 7.5 nautical miles off the Omani coast while travelling along the Omani-approved route, raising alarm among international shipping operators.
The IRGC's radio broadcasts to vessels in the strait warned: "Transit only with IRGC permission, on designated routes. No permission, AIS off, or off-route, and you carry the consequences."
The dispute complicates a fragile US-Iran memorandum of understanding (signed 17 June 2026) under which Iran committed to allowing oil tankers safe passage through the strait, and comes as both parties are in a 60-day window of negotiations toward a final deal.

Static Topic Bridges

The Strait of Hormuz: Geography and Strategic Significance

The Strait of Hormuz is a narrow waterway connecting the Persian Gulf (and the oil-rich Gulf states — Saudi Arabia, UAE, Kuwait, Iraq, Qatar, Bahrain) to the Gulf of Oman and the broader Indian Ocean. It is the world's most strategically important maritime choke point. At its narrowest, the strait is approximately 21 nautical miles wide, but the internationally used shipping lanes are only 2 nautical miles wide in each direction (inbound and outbound), separated by a 2-nautical-mile buffer zone.

Under normal conditions, approximately 21 million barrels of oil per day — about 25% of all global seaborne oil trade — transit the strait.
Approximately 20% of the world's total petroleum supply and 30% of global LNG exports pass through it.
The strait is bordered by Iran to the north and Oman to the south.
There is no viable alternative pipeline route that can replace full Hormuz capacity; the Strait has no bypass for most of the Gulf's crude exports.
Disruption of the strait directly impacts India, which imports over 85% of its crude oil, a significant share of which comes from Gulf producers.

Connection to this news: Iran's ability to threaten or restrict transit through this narrow passage gives it outsized leverage in international negotiations — the IRGC's routing demands are as much political as operational.

Transit Passage Rights Under UNCLOS

The United Nations Convention on the Law of the Sea (UNCLOS), adopted in 1982 and entering into force in 1994, establishes the international legal framework governing the use of oceans. Part III of UNCLOS specifically governs "Straits Used for International Navigation." Under UNCLOS Article 38, all ships and aircraft (civilian and military) enjoy the right of transit passage — the right to freely, continuously, and unobstructedly transit through international straits — which coastal states cannot suspend.

Transit passage (UNCLOS Part III) differs from "innocent passage" (Part II): innocent passage can be suspended by the coastal state; transit passage cannot.
UNCLOS allows the coastal state to designate sea lanes and prescribe traffic separation schemes for transit through international straits, but only to promote safe passage — not to restrict it to politically approved vessels.
Iran signed UNCLOS but has not ratified it, and does not recognise the absolute right of transit passage; instead it asserts the right to regulate transits through its territorial sea.
Oman is a party to UNCLOS and coordinated the alternative corridor with the IMO precisely on the basis of UNCLOS provisions.
The US, while not itself a party to UNCLOS, recognises transit passage rights as customary international law.

Connection to this news: Iran's IRGC insistence on controlling the specific corridor ships use — and its threat to vessels using the Omani route — is legally contested under UNCLOS, which does not permit Iran to unilaterally ban or re-route transit passage ships.

The 2026 Iran Conflict and Strait Disruption: Context

Shipping through the Strait of Hormuz was largely blocked beginning 28 February 2026, following a US-Israel air campaign against Iran, in retaliation for which the IRGC issued passage warnings, boarded and attacked merchant ships, and laid sea mines in the strait. A US naval blockade was imposed on Iranian ports on 13 April 2026 after Islamabad Talks failed. On 17 June 2026, both sides signed a memorandum of understanding to end hostilities and restore passage; the US lifted its blockade as part of this arrangement. The current dispute over routing reflects residual enforcement of Iranian sovereignty claims even within the formal ceasefire framework.

Before the war: ~17–21 million barrels/day transited the strait.
At peak disruption: tanker traffic dropped to near zero.
At least three tankers were struck near the strait during the conflict.
The 60-day post-MOU negotiation window (from ~17 June 2026) makes the current routing dispute politically sensitive.

Connection to this news: Iran's routing demands are partly a leverage tool in ongoing nuclear and sanctions negotiations — maintaining de facto control over Hormuz transit even within a ceasefire context.

AIS (Automatic Identification System) and Maritime Domain Awareness

AIS is a transponder-based system mandatory for most commercial vessels above 300 gross tonnage, under IMO regulations (SOLAS Convention). AIS broadcasts vessel identity, position, course, and speed, enabling maritime traffic management and safety. "AIS off" — switching off the transponder — is associated with suspicious or evasive maritime behaviour and makes vessels invisible to civilian tracking systems.

The IRGC explicitly warned vessels going "AIS off" or taking off-route paths face consequences.
India's Information Fusion Centre — Indian Ocean Region (IFC-IOR) at Gurugram uses AIS data and partner-shared feeds for maritime domain awareness (MDA) across the IOR.
Under IMO regulations, deliberately switching off AIS without valid safety reasons is considered a violation.

Connection to this news: The IRGC's specific mention of AIS suggests it is using commercial vessel transponder data to identify and enforce its own routing directives — and threatening vessels that go dark to avoid Iranian-corridor tracking.

Key Facts & Data

Strait of Hormuz width at narrowest: approximately 21 nautical miles
Navigable shipping lane per direction: 2 nautical miles each way
Oil transiting the strait daily (pre-war): ~21 million barrels (~25% of global seaborne oil)
LNG passing through the strait: approximately 30% of global LNG exports
Iran's ratification of UNCLOS: Not ratified (signed only)
Oman's UNCLOS status: Full party
US-Iran MOU signed: 17 June 2026
Post-MOU negotiation window: 60 days
Cargo ship struck off Omani coast: approximately 7.5 nautical miles from the Omani coast
Strait borders: Iran (north), Oman (south)