The U.S., UK and Romania said Sunday they believed Iran carried out an attack on an Israeli-owned oil tanker off the coast of Oman on Thursday that killed a Briton and a Romanian, with the UK corroborating Israel’s claim a day earlier that there is proof of Tehran’s culpability.

The UK on Monday summoned the Iranian ambassador over the incident.

Tehran denied involvement in Thursday night’s drone attack on the Mercer Street ship, saying Israel’s claim was “baseless.”

Two of the ship’s crewmen, a British and a Romanian national, died in the attack. Israeli and American officials told the New York Times that several Iranian drones were used in the strike.

Israel has said it would respond to the attack and the UK on Monday said Jerusalem “needs to make its own considerations” in that regard.

Iran on Monday warned against a retaliatory strike, saying it would hold the US and Britain responsible for any acts against it.

“Although the Islamic Republic of Iran considers the threats of Western officials and those of the Zionist regime as propaganda, any move against the interests and national security of Iran will face a tough and firm response, and Washington and London will be directly responsible for its consequences,” an Iranian official told Iran’s Nour news.
Secretary of State Antony Blinken said the US was certain that Iran was behind the attack, for which there was “no justification.”

“Upon review of the available information, we are confident that Iran conducted this attack, which killed two innocent people, using one-way explosive UAVs,” he said.

“We are working with our partners to consider our next steps and consulting with governments inside the region and beyond on an appropriate response, which will be forthcoming,” Blinken said.

The UK’s deputy ambassador to Israel Mark Power told Israel’s Kan public broadcaster that his country was provided with “clear proof” of Iran’s involvement in the attack.
“It is a clear targeted attack and a clear violation of international law,” he said, and added that the UK would send a team to investigate the incident.
Romanian Foreign Minister Bogdan Aurescu also confirmed the incriminating intel.
“Based on [the] available info, Romania strongly condemns [the] Iranian drone attack against Mercer Street, during which a [Romanian] citizen was killed,” Aurescu tweeted. “There is no justification whatsoever for deliberately attacking civilians.”
Israeli Prime Minister Naftali Bennett on Sunday said Israel had proof that Iran was “unequivocally” to blame for the attack and called on the international community to let Tehran know it had made a “serious mistake.”
“We know how to convey this message to Iran in our own ways,” Bennett warned.
“Iran’s bullying is dangerous not only for Israel, endangers not only Israel, but also harms global interests, namely freedom of maritime navigation and international trade,” the prime minister said.Iran and Israel have been engaged in several maritime scuffles in recent months, but this was the first deadly attack.