Iran’s military vowed a swift response to the US seizure of an Iranian-flagged tanker in the Gulf of Oman, state media reported on Sunday.The military headquarters said the attack and subsequent boarding of the ship by US forces was a violation of the ceasefire and denounced it as piracy, Iran’s state-run broadcaster said.The US Navy attacked and seized an Iranian-flagged cargo ship it said had tried to evade a naval blockade near the Strait of Hormuz on Sunday. The US says it fired on the ship and seized it because it had crossed the blockade line after ignoring multiple warnings.’Security of Strait of Hormuz is not free,’ says Vice President Mohammad Reza Aref amid rising US-Iran tensionsApril 20, 2026 8:16 amTehran: Iran’s First Vice President Mohammad Reza Aref on Sunday (local time) warned that stability in the Strait of Hormuz comes at a cost, stating that the country cannot be expected to ensure maritime security while facing restrictions on its own oil exports, amid escalating tensions with the United States over the seizure of an Iranian vessel. In a post on X, Aref said, “The security of the Strait of Hormuz is not free. One cannot restrict Iran’s oil exports while expecting free security for others.” He added that the consequences of continued pressure would be global in scale, particularly for energy markets.