WASHINGTON — The United States has reiterated that Iran carried out a drone attack on an Israeli-managed oil tanker off the coast of Oman last week in which a British security guard and a Romanian crew member were killed. Speaking at a regular press briefing on Monday, US Secretary of State Antony Blinken said: "I want to condemn again the attack on Friday against the commercial ship ... We"ve conducted a thorough review and we"re confident that Iran carried out this attack," Blinken said. “We have seen a series of actions taken by Iran over many months, including against shipping, so I am not sure this particular action is anything new," he said. "What it does say is that Iran continues to act with tremendous irresponsibility when it comes to, in this instance, threats to navigation, to commerce, to innocent sailors who are simply engaged in commercial transit in international waters.” “There is no justification for this attack on a peaceful vessel on a commercial mission in international waters. Iran’s action is a direct threat to freedom of navigation and commerce,” Blinken quipped. In a warning to Iran, the US secretary of state vowed a “collective response” to the attack on the MV Mercer Street owned by prominent Israeli billionaire Eyal Ofer. “We are in very close contact, in coordination, with the United Kingdom, Israel, Romania and other countries. And there will be a collective response,” Blinken told reporters. — With inputs from agencies