The United States said it welcomed Britain’s seizure of an Iranian oil tanker near Gibraltar, labeling it “excellent news,” while Tehran condemned what it called the “illegal interception” of the vessel.
"Excellent news: UK has detained the supertanker Grace 1 laden with Iranian oil bound for Syria in violation of EU sanctions," U.S. national security adviser John Bolton tweeted on July 4.
"America & our allies will continue to prevent regimes in Tehran & Damascus from profiting off this illicit trade," he wrote.
The government of Gibraltar, a British overseas territory, said British Royal Marines had boarded the supertanker, called the Grace 1, on July 4.
The ship was detained 4 kilometers south of Gibraltar in what Britain considers its territorial waters, although Spain -- which still claims the territory -- says they are Spanish waters.
The vessel is suspected of carrying crude oil to Syria’s Banias refinery, which is subject to European Union sanctions.
A spokesman for British Prime Minister Theresa May said she welcomed the "firm action" by the authorities in Gibraltar.
"We have reason to believe that the Grace 1 was carrying its shipment of crude oil to the Banyas Refinery in Syria," Gibraltar's chief minister, Fabian Picardo, said in a statement.
"That refinery is the property of an entity that is subject to European Union sanctions against Syria.
"We have detained the vessel and its cargo," Picardo said.
The EU has banned oil shipments to Syria since 2011, but this would be the first time a tanker has been seized at sea.
"This is the first time that the EU has done something so public and so aggressive. I imagine it was also coordinated in some manner with the U.S. given that NATO member forces have been involved," Matthew Oresman, a partner with law firm Pillsbury Winthrop Shaw Pittman who advises firms on sanctions, was quoted by Reuters as saying.
"This is likely to have been meant as a signal to Syria and Iran -- as well as the U.S. -- that Europe takes sanctions enforcement seriously and that the EU can also respond to Iranian brinkmanship related to ongoing nuclear negotiations," he added.
Reuters reported that shipping data it had reviewed suggested the tanker was carrying Iranian oil loaded off the coast of Iran, although official documents contend the oil is from Iraq.
Iran summoned the British ambassador in Tehran over what it called the "illegal seizure" of the tanker.
"After the illegal interception of an Iranian oil tanker in the strait of Gibraltar by the English naval force, that country's ambassador to Tehran was summoned to the Foreign Ministry," ministry spokesman Abbas Moussavi said.
The seizure comes at a time of especially high tensions between the West, especially the United States and Iran.
U.S. President Donald Trump in May 2018 withdrew from the 2015 nuclear deal that Iran signed with world powers and began reimposing sanctions that had been eased in return for curbs on Tehran’s nuclear program.