An allied force led by British soldiers seized an Iranian oil tanker on Thursday, July 4 under suspicion the vessel was transporting crude oil to a Syrian refinery in violation of sanctions. The strike force was composed of British Royal Marines aiding authorities from Gibraltar. Some reports indicate that intelligence and a request for action originated from U.S. authorities. 

Iran has threatened to take an oil tanker flying a British flag in retaliation, which BBC reports the Islamic Republic has the capability to do and would see as a proportionate response. Iran has claimed the tanker was not destined for the Baniyas Refinery in Tartous, Syria. Iranian officials have declined to state the true destination of the tanker, but claim the port to be incapable of handling the size of the ship and its cargo. The ship and cargo are reputed to be worth $200 million.

Iranian defense minister, Amir Hatami said British action “will not be tolerated by us and will not go without a response” in a live speech on Iranian state television. 

“This is an incorrect and wrong action, an action similar to maritime robbery,” Hatami said. “Certainly, these types of robberies will not be tolerated.”

Iran disputes that it is forbidden from selling crude to Syria as it is not a member of the European Union and is not subject to a European embargo.

U.S. officials have attempted to bring European allies onboard with sanctions intended to cripple Iran’s ability to create nuclear weapons and fund terrorist organizations. So far, Europe and Britain have been reluctant to join the U.S. position, but the recent bombing of two petrochemical tankers has increased tensions between Iran and the UK. 

The tanker was initially detained on a 72-hour hold. The Supreme Court of Gibraltar has granted a 14-day hold to discover the facts in the matter. Iranian deputy foreign minister, Abbas Araghchi said Iran is seeking a solution through the courts and hoped the situation could be resolved by diplomacy. 

On Tuesday, Major General Mohammad Bagheri told Tasnim news agency that “Capture of the Iranian oil tanker based on fabricated excuses … will not be unanswered and when necessary Tehran will give appropriate answer.”

The Wall Street Journal, quoting an unnamed source, said a British tanker operated by BP PLC has taken shelter in Saudi Arabian territory over fears of a takeover. BP has not confirmed the location of the tanker but reports it is keeping the ship in the region.

The sanctions instituted by the U.S. originated after the Trump administration removed its signature from a deal made in 2015 to ensure Iranian compliance with EU nuclear refinement regulations in an effort to prevent Iran from becoming a nuclear-weapon-capable nation. 

Trump believes the deal allows Iran to profit through oil sales and funds terrorist organizations. Iran has promised to continue violating the agreement it still holds with European nations unless the U.S. drops sanctions.