According to Reuters, the US filed a lawsuit to seize the cargo, alleging that Iran masked the origin of the oil by transferring it to several vessels before it ended up aboard the Liberian-flagged Achilleas tanker destined for China. It added that the cargo contravened U.S. terrorism regulations.

The Achilleas last reported its positionas anchored within the Galveston Offshore Lightering Area, outside the U.S. Gulf port of Galveston.

Commenting on the situation, a U.S. official said last week that the US had sold more than a million barrels of Iranian fuel seized under its sanctions program last year.

Tensions have increased between Washington and Tehran since 2018, when former U.S. President Donald Trump abandoned Iran’s 2015 nuclear deal with six major powers and reimposed sanctions on the country.

U.S. President Joe Biden has pledged to revive the nuclear deal if Iran returns to full compliance with the accord.