The US issued a warrant to seize an Iranian oil tanker in an eleventh-hour attempt to prevent the ship from leaving Gibraltar.

The Grace 1 was seized by British officials July 4 because it was suspected of violating European Union sanctions prohibiting the sale of oil to Syria.

The seizure led to a tit-for-tat that saw Iran seize three oil tankers sailing through the Persian Gulf.

Gibraltar removed a detention order Thursday, allowing the Grace 1 to leave, after the British territory’s chief minister said Tehran pledged the 2.1 million barrels of oil it’s carrying would not go to Syria.

The U.S. warrant seeks to take control of the tanker and $995,000 aboard, citing violations of US sanctions, money laundering and terrorism statutes, the Associated Press reported. The situation could go back to Gibraltar’s Supreme Court.