Was Iran’s Seizure of a British Ship Legal?

On Friday, July 19, the Revolutionary Guards seized a British-flagged oil tanker, the Stena Impero, in the strategic Hormuz Strait, claiming it was “violating international maritime rules.” The British government has demanded Iran release the tanker without delay, and British Foreign Secretary Jeremy Hunt warned that Iran would face “serious consequences” if the situation is not resolved quickly.

So was Iran’s seizure of the tanker legal under international laws? What is the process for detaining a tanker? And what did Hunt mean by “serious consequences” ?

 

Why did Iran seize Stena Impero?

Iranian official news agencies say that Stena Impero had entered the Strait of Hormuz from the south and had turned off its automatic identification system (AIS), which is used to identify and track ships. Iran claims the vessel was seized after it collided with a fishing boat and failed to respond to distress calls from the smaller craft.

 

Are Iran’s reasons valid?

According to the current rules in place, ships must enter the Persian Gulf through the north of the Strait of Hormuz but, according to Iranian officials, Stena Impero was entering the gulf through the southern waters of the strait. The rules resemble road regulations, and the instance was similar to a car driving on the wrong side of a highway — a serious risk to the safety of navigation.

Iran and Oman control the north and the south of the Strait of Hormuz respectively and, in order to ensure the safety of navigation, they can call on a vessel to change its course — and seize the vessel if it ignores this demand.

 

Could the Revolutionary Guards have acted independently?

At the time of its seizure, Stena Impero was not in a location where the Revolutionary Guards could have seized it using its own independent initiative. Iran’s Ports and Maritime Organization is responsible for the oversight and control of international navigation rules in Iranian waters. If this organization concludes that a vessel has been violating navigation rules within Iranian waters then it must appeal to judiciary officials to issue a warrant to detain the vessel. After such a warrant is issued, the Iranian military must issue the warrant and seize the vessel.

 

How do officials seize an oil tanker?

If the vessel is outside the 12 miles of Iranian territorial waters, then the military must order the vessel to enter its territorial waters. Prior to the vessel entering these waters, the military is not allowed to board the vessel in order to seize it. But when a vessel enters territorial waters, the military has the jurisdiction to board, inspect and seize that vessel. For this reason, the navies of countries including the United States and the United Kingdom are on guard in the Persian Gulf. One of their missions is to confront the Iranian military if it acts to seize vessels using its own navy ships.

 

Why did the Revolutionary Guards and not Iran's regular navy seize the tanker?

According to the Islamic Republic’s internal division of responsibilities, the Iranian regular navy is responsible for protecting Iranian waters in the Gulf of Oman, while the responsibility for the Strait of Hormuz and the Persian Gulf falls on the Revolutionary Guards’ navy. Therefore, vessels that navigate from the Hormuz Strait into the Persian Gulf must deal with the Revolutionary Guards' navy and it is this naval force that carries out any seizures.

 

What are the potential consequences?

The strait of Hormuz is an international waterway and it is the responsibility of Iran and Oman to ensure the safety of commercial navigation in its waters. If a vessel violates international navigation rules or is suspected of doing so, then it can be seized, but a decision about the vessel must be made soon after the preliminary investigations. If the vessel has broken the rules, the country that owns it is obliged to pay a file and if the violation is at a level that must be referred to court — a process that is usually long and time-consuming — the vessel’s owner, its captain and crew, and the country of the flag the vessel is flying must be informed of the situation. The government that has seized the vessel must present convincing reasons for continuing to hold the vessel.

 

What are the current assumptions about the seizure?

On July 4, the British Royal Marines boarded and detained an Iranian supertanker in the Strait of Gibraltar. The port authority of Gibraltar, a British jurisdiction, said the tanker was carrying crude oil from Iran to Syria, a violation of European Union sanctions against Syria.

Iranian officials described the seizure as an act of “piracy,” and leading Iranian figures from the Supreme Leader Ayatollah Khamenei to Mohsen Rezaee, the Secretary of the Expediency Council, threatened retaliation. It is possible that Britain’s Stena Impero turned off its transponders in order to escape detention and the risk of retaliation from Iran, and decided to enter the Persian Gulf through southern waters of the Strait of Hormuz. If this is the case, then seizure of it could be justified.

But regardless of whether the move was justified or not, the Islamic Republic had threatened retaliation, so the seizure has been interpreted as a response that could heighten tensions in the Persian Gulf. The other possibility is that Iran’s claims are false and the seizure was simply a retaliatory move. If that is the case, then tensions are bound to rise.

 

Related Coverage:

The IRGC Navy, April 9, 2019

Britain to Hit Iran with Sanctions After Brexit, February 10, 2019

Can Iran Legally Close the Strait of Hormuz?, July 5, 2018