US President Donald Trump said the United States is taking serious measures in response to Saturday's attack by the Islamic State group in Syria, which killed three Americans - two service members and one civilian.

He wrote about this on Saturday on his social network Truth Social, Ukrinform reports.

"This was an ISIS attack against the United States and Syria in a very dangerous area of Syria that they (the Syrian government, ed.) do not fully control," Trump said.

According to him, Syrian President Ahmed al-Sharaa is angry and concerned about this attack.

In addition to the three dead, three other US service members were injured. Trump said they are doing well.

"There will be very serious retaliation," Trump said.

It was the first fatal attack on US troops in Syria since the fall of Bashar al-Assad's regime a year ago.

As reported by AP, according to the US Central Command, the attack was carried out from an ambush set up by a single ISIS militant in central Syria. The attacker was eliminated.

Pentagon spokesman Sean Parnell said the civilian who died was a translator. He said the attack was directed against military personnel involved in counterterrorism operations in the region.

The Syrian Interior Ministry said an armed attacker linked to ISIS opened fire at the gate of a military post.

The US maintains several hundred troops in eastern Syria as part of the coalition fighting ISIS. The group was defeated on the battlefield in 2019, but the UN says it maintains between 5,000 and 7,000 fighters in Syria and Iraq and continues to carry out attacks.

As Ukrinform reported, the American military, together with the Syrian Ministry of Internal Affairs, destroyed about a dozen ISIS weapons caches.