The US and UK openly blamed Iran for Thursday’s drone attack on an oil tanker operated by an Israeli-owned firm.
The MV Mercer Street was attacked off Oman on Thursday leaving two dead, and in separate statements on Sunday, the countries’ top diplomats have vowed to respond, calling it a violation of international law.
A Briton and a Romanian were killed.
US Secretary of State Anthony Blinken said the country is “confident” Iran was behind this drone attack.
“Upon review of the available information, we are confident that Iran conducted this attack, which killed two innocent people, using one-way explosive UAVs, a lethal capability it is increasingly employing throughout the region,” Blinken said in a statement.
“There is no justification for this attack, which follows a pattern of attacks and other belligerent behavior. These actions threaten freedom of navigation through this crucial waterway, international shipping and commerce, and the lives of those on the vessels involved,” he added.
“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. We once again offer our condolences to the families of the victims,” the secretary continued.
British Foreign Secretary Dominic Raab said it was “highly likely” that Iran was behind the attack.
“We believe this attack was deliberate, targeted, and a clear violation of international law by Iran. UK assessments have concluded that it is highly likely that Iran attacked the MV Mercer Street in international waters off Oman on 29 July using one or more Unmanned Aerial Vehicles,” Raab said in a statement.
The statements came after Israel’s Prime Minister Naftali Bennett said there was “evidence” that its longstanding foe Iran was responsible.
Mr Bennett warned that “we know how to send a message to Iran in our own way”, while Tehran rejected what it called the “baseless accusations”.
The attack on the MV Mercer Street appears to be the latest escalation in an undeclared “shadow war” between Israel and Iran.
Since March there have been several attacks on both Israeli and Iranian-operated vessels, which are seen as tit-for-tat incidents. Casualties are considered rare.
Iran has also accused Israel of targeting its nuclear sites and scientists.
Israel’s Prime Minister said it expected the international community to make clear to Iran that it had made a serious mistake.
Iran conceded nothing in response. Its foreign ministry spokesman, Saeed Khatibzadeh, told reporters that “the Zionist regime (Israel) has created insecurity, terror and violence”.
He said Israel “must stop such baseless accusations”, warning: “Whoever sows the wind reaps the whirlwind.”
The escalation comes against the backdrop of key nuclear talks in Vienna. Officials are attempting to revive a 2015 international deal under which sanctions on Iran are lifted in return for commitments from Tehran to curb its nuclear programme.