US Secretary of State Mike Pompeo said Washington will take every action it can to prevent an Iranian oil tanker that left Gibraltar on Monday from delivering oil to Syria in contravention of current American sanctions.

The vessel was released from six-week detention off the British territory of Gibraltar on Sunday evening after a local court accepted Iranian assurances that the ship was not bound to Syria. The vessel was taken over by British Royal Marines in July for carrying oil to Syria – a gross violation of EU sanctions.

The tanker is reportedly headed for Greece where the new conservative government said the vessel is not welcome to Greece.

In an interview with ANT1 TV on Wednesday, Alternate Foreign Minister Miltiadis Varvitsiotis said Greece was not willing to facilitate the transfer of oil to Syria. He also added that the ship, Adrian Darya 1, is too big to dock in the country’s southern port of Kalamata.

The Greek Foreign Ministry’s state also indicated that Athens does not accept any assurances by the government of the Islamic Republic of Iran that the supertanker is not bound for Syria.

Maritime Affairs Minister Yiannis Plakiotakis confirmed that the Iranian government never officially requested that the ship dock in Greece, comments that came shortly after Pompeo said the White House will slap sanctions on any nation that allows the tanker to drop anchor in their respective harbours.

Although the EU has not completely followed the US in imposing harsh oil export sanctions on Iran, many members of the bloc EU have unilaterally imposed stiff oil sanctions on the Bashar al-Assad regime – the Islamic Republic’s ally.

Washington has linked the supertanker to Iran’s Islamic Revolutionary Guard Corps – the single-most powerful military and economic entity in Iran that was designated as a terrorist organisation by the governments of Bahrain, Saudi Arabia, and the United States for its open backing of radical terrorist groups, including Hamas in the Gaza Strip, Egypt’s Muslim Brotherhood, Hezbollah in Lebanon, the Hashd al-Shaabi Shiite militias in Iraq, and Yemen’s Houthi rebels.

Brussels, which has tried to maintain good relations with the theocratic regime in Tehran, has not followed the US’ lead in pronouncing the Revolutionary Guards as a terrorist organisation, though it does have sanctions in place against the group. The UK, Canada, and Australia are looking into the possibility of listing the Revolutionary Guards, or IRGC, as a terrorist entity following its disruption of international shipping traffic in the Strait of Hormuz.

The US Department of Justice issued a warrant to seize the vessel on Sunday evening, but the court ruled that Gibraltar is not bound by American oil export sanctions.