The US military has carried out multiple air strikes in Syria against Iran-aligned groups who it blamed for a deadly drone attack that killed a contractor, injured another and wounded five US troops, the Pentagon said.
The strikes were in retaliation for an attack against a US-led coalition base near Hasakah in north-east Syria on Thursday, it said.
The US intelligence community assessed that the drone was Iranian in origin, the military said.
US Defense Secretary Lloyd Austin said the strikes targeted groups affiliated with Iran's Islamic Revolutionary Guards Corps.
"The air strikes were conducted in response to today's attack as well as a series of recent attacks against coalition forces in Syria by groups affiliated with the IRGC," Mr Austin said in a statement.
Overnight, video on social media purported to show explosions in Syria's Deir Ez-Zor, a strategic province that borders Iraq and contains oil fields.
Iran-backed militia groups and Syrian forces control the area, which also has seen suspected air strikes by Israel in recent months allegedly targeting Iranian supply routes.
Iran's paramilitary Revolutionary Guard, which answers only to Supreme Leader Ayatollah Ali Khamenei, has been suspected of carrying out attacks with bomb-carrying drones across the wider Middle East.
In recent months, Russia has begun using Iranian drones in its attacks on sites across Ukraine as part of its war on Kyiv.
Iran has denied being responsible for these attacks, though Western nations and experts have tied components in the drones back to Tehran.
The attack and the US response threaten to up-end recent efforts in the region to de-escalate tensions, as Saudi Arabia and Iran have been working toward reopening embassies in each other's countries.
The kingdom also acknowledged efforts to reopen its embassy in Syria, whose embattled President Bashar Assad has been backed by Iran in his country's long war.
Syria's state-run SANA news agency did not immediately acknowledge any strikes.
US Army General Michael Kurilla, the head of the American military’s Central Command, warned that American forces could carry out additional strikes if needed.
"We are postured for scalable options in the face of any additional Iranian attacks," General Kurilla said in a statement.
Syria's mission to the United Nations did not immediately respond to a request for comment.
There was no immediate reaction from Iran over the strikes, which come during the holy Muslim fasting month of Ramadan.
Qatar's state-run news agency reported a call between its foreign minister and Jake Sullivan, the US national security adviser.
Doha has been an interlocutor between Iran and the US recently amid tensions over Tehran's nuclear program.
Mr Austin said he authorised the retaliatory strikes at the direction of US President Joe Biden.
"As President Biden has made clear, we will take all necessary measures to defend our people and will always respond at a time and place of our choosing," Mr Austin said.
"No group will strike our troops with impunity."
The Pentagon said two of the wounded service members were treated on-site, while three others and the injured contractor were transported to medical facilities in Iraq.
ABC/wires
