A US contractor was killed and another hurt alongside five American armed forces personnel when a suspected Iranian drone attacked a facility on a coalition base in north-east Syria, the Pentagon said.

Defence secretary Lloyd Austin said US Central Command forces hit back with “precision airstrikes” against facilities in eastern Syria used by groups affiliated with Iran’s Revolutionary Guard.

The intelligence community determined the unmanned aerial vehicle was of Iranian origin, the defence department said.

“The airstrikes 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 Revolutionary Guard, Mr Austin said on Thursday night.

Videos on social media purported to show explosions in Syria’s Deir ez-Zor, a strategic province bordering Iraq and containing oil fields.

Iran-backed militia groups and Syrian forces control the area, which also has seen suspected airstrikes 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 upend recent efforts in the region to deescalate 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.

US army General Michael “Erik” Kurilla, the head of the American military’s Central Command, said American forces could carry out additional strikes if needed.

“We are postured for scalable options in the face of any additional Iranian attacks,” he said in a statement.

Syria’s state-run SANA news agency did not immediately acknowledge any strikes.

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.

Iran’s mission to the United Nations did not immediately respond to a request for comment.

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 programme.

Qatar’s foreign minister also spoke around the same time with Iranian foreign minister Hossein Amirabdollahian.

Mr Austin said he authorised the retaliatory strikes at the direction of President Joe Biden.

The US under Mr Biden has struck Syria previously over tensions with Iran.

In February and June of 2021, as well as August 2022, Mr Biden launched attacks there.

US forces entered Syria in 2015, backing allied forces in their fight against the so-called Islamic State group.

The US still maintains the base near Hasakah in north-east Syria where Thursday’s drone strike happened.

There are roughly 900 US troops and even more contractors in Syria, including in the north and further south and east.

“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.”

Syria’s war began with the 2011 Arab Spring protests that roiled the wider Middle East and toppled governments in Egypt, Libya, Tunisia and Yemen.

It later morphed into a regional proxy conflict that has seen Russia and Iran back Mr Assad.

The United Nations estimates more than 300,000 civilians have been killed in the war.

Those figures do not include soldiers and insurgents killed in the conflict; their numbers are believed to be in the tens of thousands.

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.