Revolutionary Guards’ Seizure of British Tanker Violated International Laws

July 23, 2019
Faramarz Davar
5 min read
When it seized the British oil tanker in the Strait of Hormuz, the Revolutionary Guards violated international laws and conventions in four areas
When it seized the British oil tanker in the Strait of Hormuz, the Revolutionary Guards violated international laws and conventions in four areas

When the Revolutionary Guards seized a British-flagged oil tanker on Friday, July 19 in the strategic Strait of Hormuz, the Guards and Iranian government officials offered competing justifications for the action. But as further information came to light in the following days, it emerged that Iran had in fact violated international laws and regulations when it seized the ship, the Stena Impero. 


1. The Guards Violated the UN Convention on the Law of the Sea.

The Strait of Hormuz is a narrow waterway and all vessels, including oil tankers, must navigate through the territorial waters of Iran and Oman in order to cross it. Territorial waters are considered part of a country’s territory and the government of that country has the right to set its own navigation rules in those waters after consulting with the United Nations’ International Maritime Organization (IMO). The rules and regulations cannot violate international laws and the Convention on the Law of the Sea (UNCLOS).

According to this convention, when vessels have no other way but to navigate through the territorial waters of a country in order to cross a strait then the strait is considered “international” and the littoral country must not only allow freedom of passage to vessels but it must not disrupt their navigation and stop them either, even for a short time.

UNCLOS was adopted and signed in 1982 but since that time, the Islamic Republic has repeatedly objected to this provision in the convention and declared that it only recognizes this right for vessels carrying the flag of countries that obey the same rule. Britain is a member of this convention and has recognized this provision, but the Revolutionary Guards ignored this fact and seized the British oil tanker in violation of the convention and international law.


2. The British Tanker was Seized in Oman’s Territorial Water

At first the Revolutionary Guards claimed that the Stena Impero had entered the Strait of Hormuz through the wrong direction — from the south instead of from the north — and that it had turned off its automatic identification system (AIS), which is used to identify and track ships. But the British have now released maps that trace the route taken by the tanker and the location where it was seized. The maps show that the tanker’s AIS was not turned off and, furthermore, the tanker was seized when it was moving in the right direction in both the territorial waters of Oman and those of Iran.

In crossing the Strait of Hormuz, most ships navigate through Oman’s territorial waters because these waters are deeper and can allow for heavy ships to cross. Needless to say, Iran has no legal right to control or block Oman’s territorial waters.

In other words, by seizing the British tanker when it was navigating a lawful course in an international strait and in the territorial waters of another country, the Revolutionary Guards first militarily violated the territory of another country and, second, broke international law by denying the freedom of navigation to the ship.


3. Retaliation instead of Counteraction

According to accepted international practices, a country has the right to counteract if it has been the target of an illegal act by another country. For instance, if a country expels the diplomats of another country, the second country has the right to expel the diplomats of the first country but the counteraction must be proportionate and not resort to violence or military force.

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. In response, Iranian political and military leaders threatened Britain with retaliation.

“The Islamic Republic...will not let these evil deeds go unanswered and it will respond to them in the right place and at the right time,” said the Supreme Leader Ayatollah Khamenei after the Iranian tanker was detained. And two days after Khamenei’s threat, the Revolutionary Guards detained two British tankers. It released one but kept the Stena Impero.

In his statements, Minister of Defence Brigadier General Amir Hatami pointed to British authorities’ detention of the Iranian tanker in the Strait of Gibraltar and said: “we immediately took action against them in the Persian Gulf.” His statements make it clear that the Revolutionary Guards’ action was “retaliatory” not counteractive, something that is considered illegal under international law. Maybe it was for this reason that the government’s spokesman shortly afterwards denied the defense minister’s statement and emphasized that the seizure of the British tanker was not an act of retaliation.

“Counteraction” cannot resort  to violence or military force, and yet the detention of the British tanker was carried out by heliborne troops and the Revolutionary Guard’s swift boats and the troops seized the ship after boarding it. If this action taken by the Revolutionary Guards was a retaliation, then it was an illegal act under international law. But it was also illegal as a counteraction because force was used.


4. Trespass and the Call to Prayer on the Tanker

A few hours after Iran seized the British taker, an Iranian news agency posted a video in which the Islamic call to prayer (adhan) can be heard being broadcast on the ship’s loudspeakers. The video was taken from a Revolutionary Guards’ swift boat, which also shows the Guards’ flags fluttering over the tanker.

Prior to this, Iranian media affiliated with the Revolutionary Guards posted videos of Guards’ swift boats taking “joyrides” around the tanker after it had been detained and had dropped anchor in Iranian waters. Legally, such actions, as well as the broadcast of the call to prayer inside the captured ship are considered to be trespasses. So this is yet another violation of international law, all in connection with the seizure of the British oil tanker.


Related Coverage:

Was Iran’s Seizure of a British Ship Legal?, July 20, 2019

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






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