An Iranian Revolutionary Guard Corps commander threatened to seize a British ship in retaliation for the Royal Marines capture of an Iranian tanker in Gibraltar.

“If Britain does not release the Iranian oil tanker, it is the authorities’ duty to seize a British oil tanker,” IRGC commander Mohsen Rezai tweeted on Friday.

The British Royal Marines seized the ship on Thursday, accusing it of being bound for Syria, U.S. and EU sanctions are in place to prevent oil sales to the country. The sanctions caused dire fuel shortages in the winter, forcing the government to ration fuel and ordinary Syrian’s struggled to heat their homes.

A senior Iranian official condemned the seizure and “called for the immediate release of the oil tanker, given that it has been seized at the request of the US, based on the information currently available,” in a statement released by the Iranian foreign ministry Friday.

The Spanish Foreign Minister also said the British seized the ship on behalf of the U.S., no U.S. officials have admitted to giving the order but National Security Advisor John Bolton celebrated the seizure on Thursday in a tweet.

“Excellent news: UK has detained the supertanker Grace I laden with Iranian oil bound for Syria in violation of EU sanctions. America & our allies will continue to prevent regimes in Tehran & Damascus from profiting off this illicit trade,” Bolton wrote on Twitter.

The government of the British territory of Gibraltar said they received orders Friday to hold the tanker for another 14 days, “The Supreme Court has issued today’s order on the basis that there are reasonable grounds to consider that the detention of the Grace 1 is required for the purposes of compliance with the EU Regulation 36/2012 on sanctions on Syria.”