The U.S. military and the Group of Seven (G7) leading industrialized countries blamed Iran on August 6 for last week's attack on a tanker in international waters off Oman.
The U.S. military’s Central Command said it had collected and examined evidence of a drone strike on the Mercer Street in the Arabian Sea last week that killed one British security guard and the ship's Romanian captain.
"U.S. experts concluded based on the evidence that this UAV was produced in Iran," Central Command said in a statement, using the acronym for unmanned aerial vehicle.
Meanwhile, G7 countries condemned what they called an "unlawful attack" on the vessel, which is managed by a U.K.-based company owned by Israeli billionaire Eyal Ofer.
"All available evidence clearly points to Iran," the foreign ministers of Britain, Canada, France, Germany, Italy, Japan, and the United States said in a joint statement.
Following the July 30 attack, first Israel, then the United States and Britain pointed the finger at Tehran and vowed repercussions for such a threat on international shipping.
Tehran has denied any role in the attack.
Central Command, which covers the Middle East, said the Mercer Street was first targeted by two unsuccessful drone attacks on July 29. Investigators found the remnants of at least one of the drones pulled from the water.
A third drone loaded with a "military-grade explosive" hit the pilot house of the ship on July 30, creating a roughly two-meter hole and causing damage to the interior, Central Command said.
Investigators were able to recover part of the wing and internal components from the third drone "which were nearly identical to previously-collected examples from Iranian one-way attack UAVs," also known as kamikaze drones, the U.S. military said.
It said the triangle-shaped Delta wing drones are similar to those “actively used by Iran and their proxies” in the region, including against Saudi Arabia, in a reference to Yemen’s Iran-backed Huthi rebels, and bases housing U.S. forces in Iraq.
In their statement, G7 foreign ministers said "Iran’s behavior, alongside its support to proxy forces and non-state armed actors, threatens international peace and security."
European countries and the United States added to their accusations at a closed-door Security Council meeting at UN headquarters in New York on August 6.
"The UK knows that Iran was responsible for this attack. We know it was deliberate and targeted," said British Ambassador to the UN Barbara Woodward.
"The door for diplomacy and dialogue remains open. But if Iran chooses not to take that route, then we would seek to hold Iran to account and apply a cost to that," she told reporters.
Iran's deputy ambassador at the United Nations, Zahra Ershadi, rejected the accusation.
She accused Israel of trying to divert world opinion from its "crimes and inhumane practices in the region," repeating a claim that it had attacked over 10 commercial vessels carrying oil and goods to Syria.
Ershadi was referring to an expansion of a shadow war between Iran and Israel, that in recent months has seen vessels linked to each nation being mysteriously targeted in waters around the Middle East.
On August 5, Israeli Defense Minister Benny Gatz said that his country is prepared to strike Iran, ratcheting up rhetoric at a time Tehran is breaching key planks of a 2015 nuclear deal in response to the U.S. exit from the pact.
Tensions have risen in the Middle East since the United States reimposed sanctions on Iran in 2018 after then-President Donald Trump withdrew the United States from the nuclear deal with major powers.
The Pentagon said U.S. Defense Secretary Lloyd Austin spoke on August 6 with Gantz about the ship incident.
Both "expressed concern about Iran's proliferation and employment of one-way attack UAVs across the region and committed to continue cooperating closely on regional security," the Pentagon said in a statement.
"They agreed to work together alongside allies and partners in condemning Iran’s aggression that undermines freedom of navigation, and they exchanged views on next steps," it added.