Iran was under mounting pressure on Friday over a drone that struck the Mercer Street oil tanker in the Arabian Sea last month, with condemnation coming from UN and G7 members as new evidence of Iranian culpability surfaced.
The US military's Central Command (Centcom) said on Friday that military experts visited the Israeli-connected Mercer Street after the attack and found that the drone used was made by Iran.
Iran, meanwhile, faced further criticism from the G7 group of wealthy democracies as Britain, the US and European nations pushed for action against Tehran in the UN Security Council.
US explosives experts from the USS Ronald Reagan aircraft carrier found evidence that the tanker had twice been the target of drones off the coast of Oman on the evening of July 29, before it was struck in an attack on July 30.
“This UAV [unmanned aerial vehicle] was loaded with a military-grade explosive and caused the death of two crew members: the master of the ship, a Romanian citizen, and a United Kingdom national who was part of the security detail,” Centcom said.
The blast created an approximately two-metre hole in the topside of the pilot house and badly damaged the interior, Centcom said.
Chemical tests showed a nitrate-based explosive the experts identified as RDX, indicating the drone “had been rigged to cause injury and destruction".
After retrieving parts of the drone, including a piece of the wing and internal components, the US experts found these to be “nearly identical” to previously collected Iranian attack drones.
“The distance from the Iranian coast to the locations of the attacks was within the range of documented Iranian one-way attack UAVs,” Centcom said.
“US experts concluded based on the evidence that this UAV was produced in Iran.”
Iran has denied responsibility for the attack.
Centcom said it shared its evidence with British and Israeli explosives experts who agreed with the US findings.
The attack has been condemned by the international community and the US has vowed there would be a “collective response”.
On Friday, G7 foreign ministers said in a statement that the assault was a clear breach of international law, “deliberate and targeted”.
“All available evidence clearly points to Iran. There is no justification for this attack,” the G7 statement said.
“Vessels must be allowed to navigate freely in accordance with international law. We will continue to do our utmost to protect all shipping, upon which the global economy depends, so that it is able to operate freely and without being threatened by irresponsible and violent acts.”
UN Security Council members discussed the attacks behind closed doors on Friday and will meet again at the ministerial level on Monday to address the Mercer Street incident and other maritime security threats.
“The UK knows that Iran was responsible for this attack. We know it was deliberate and targeted,” Britain's UN ambassador Barbara Woodward said after the meeting.
Britain will “seek to hold Iran to account and apply cost” over the loss, she said.
The Pentagon reported that US Defence Secretary Lloyd Austin had spoken with his Israeli counterpart Benny Gantz about the attack and "expressed concern about Iran’s proliferation and employment of one-way attack UAVs across the region and committed to continue co-operating closely on regional security".
The company that operates the Mercer Street belongs to Israeli tycoon Eyal Ofer.