Iranian forces boarded two Greek Suezmax tankers - Delta Poseidon and Prudent Warrior – on 27 May in retaliation for Greek authorities stating it would hand over to the US around 700,000 barrels of Iranian crude onboard a seized Russian Aframax tanker. Iranian military helicopters boarded both vessels in international waters and re-routed them to Iranian waters. Both vessels carried Iraqi crude from Basrah Oil Terminal destined for the US according to Lloyd’s List, a shipping journal. Tehran’s Ministry of Foreign Affairs confirmed that the crew were in good health and in telephone contact with their families. It urged Athens not to involve Washington in the dispute. The move elevates risk levels for shipping in the Gulf.