The United States has issued a warning to Greece as well as to all ports in the Mediterranean Sea about providing assistance to an Iranian tanker that Washington suspects of transporting oil to Syria and having ties to a sanctioned organization, Reuters reported, citing a U.S. State Department official.

Any aid would be interpreted as providing material support to Iran's Islamic Revolutionary Guards Corps (IRGC), which Washington considers a foreign terrorist organization. Facilitating the tanker carries potential immigration and criminal consequences, the unidentified U.S. State Department official said on August 19.

The warning concerns the Adrian Darya 1, formerly known as Grace 1, a supertanker that left Gibraltar on August 19 after spending 45 days in detention over British suspicions that it was violating European Union sanctions on Syria.

Officials in Gibraltar on August 18 rejected a U.S. request to seize the tanker, letting it sail with $130 million worth of crude oil.

U.S. Secretary of State Mike Pompeo said the tanker's release was 'unfortunate' in an August 19 interview on Fox News Channel.

If Iran turns a profit from the tanker's load, the IRGC will have 'more money, more wealth, more resources to continue their terror campaign,' Pompeo said.

Online vessel-tracking sites like Refinitiv show the vessel is heading toward Kalamata, Greece, and is scheduled to arrive on August 25.

Iranian Foreign Ministry spokesman Abbas Musavi said on August 19 that Tehran had warned the United States against seizing the tanker in open seas.

'Iran has given necessary warnings to American officials through its official channels...not to make such a mistake because it would have grave consequences,' Musavi told reporters at a news conference.

This and other shipping disputes have come amid rising tensions between Iran and the West over U.S. sanctions and mounting military and commercial incidents in and around the Persian Gulf, which sees around one-fifth of international oil shipments.

The Grace 1 was seized by Royal Marines as it entered the Mediterranean Sea on July 4, reportedly carrying over 2 million barrels of Iranian oil.

After Gibraltar withdrew its five-week-old detention order against the Grace 1 on August 15, the U.S. Justice Department issued a warrant over its alleged connections to the IRGC, an arm of the Iranian military.

The U.S. warrant said the Grace 1, all of the oil aboard, and $995,000 were subject to forfeiture, citing what it called violations of the International Emergency Economic Powers Act and bank fraud, money-laundering, and terrorism statutes.

Iranian officials have insisted the tanker's cargo hold of oil is not bound for Syria.

Shipping tensions increased with Iran's seizure of a U.K.-flagged tanker, the Stena Impero, near the Strait of Hormuz later in July in what they suggested was a tit-for-tat move.

Musavi said on August 19 that there was no link between the two ships 'whatsoever.'

'There have been two or three maritime violations made by that ship,' he said in reference to Stena Impero.

'The court is looking into it. We hope the [investigation] is completed as soon as possible and the verdict is issued,' he added.

U.S. President Donald Trump has called for an international effort to escort vessels to defend commercial shipping interests in the Persian Gulf against harassment and illegal interference, meeting with support from the U.K. and from some other Western and Persian Gulf state officials.

But Iranian officials, who have routinely said the Strait of Hormuz is under their close watch, said recently that 'outside presences' in the region can destabilize things.

Then on August 18, Reuters quoted the IRGC's naval chief as warning that the presence of the United States and Britain in the region 'means insecurity' and seemingly suggested its own regional coalition to provide security in the gulf.

With reporting by TASS, AP, Reuters, AFP, and dpa

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