On May 27, the Islamic Revolutionary Guard Corps (IRGC) Navy detained two Greek-flagged oil tankers in the Persian Gulf, the Delta Poseidon and the Prudent Warrior, after accusing the ships of unspecified "violations." The IRGC also detained the tankers' crews, including two Greek citizens. According to the Greek foreign ministry, the vessel was seized in international waters. In April, Greece impounded the Pegas, an Iranian-flagged tanker with a Russian crew, under the authority of European Union sanctions. Greek authorities then allowed the United States to seize the vessel's oil. While Greece later released the Pegas, a news agency affiliated with Iran's security forces suggested that Iran would retaliate with "punitive action."