Donald Trump promises 'serious retaliation' after two US soldiers and interpreter killed in Syria by Islamic State gunman

Three other service members were injured in the attack, officials said, before the gunman was then "engaged and killed".

The identities of the three killed are being withheld for 24 hours, until their next of kin can be informed.

Mr Trump wrote on Truth Social: "We mourn the loss of three Great American Patriots in Syria, two soldiers, and one Civilian Interpreter.

"Likewise, we pray for the three injured soldiers who, it has just been confirmed, are doing well.

"This was an ISIS attack against the U.S., and Syria, in a very dangerous part of Syria, that is not fully controlled by them.

"The President of Syria, Ahmed al-Sharaa, is extremely angry and disturbed by this attack.

"There will be very serious retaliation."

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US Defence Secretary Pete Hegseth said: "Let it be known, if you target Americans - anywhere in the world you will spend the rest of your brief, anxious life knowing the United States will hunt you, find you, and ruthlessly kill you."

The ambush took place in Palmyra, central Syria, Pentagon spokesperson Sean Parnell said.

A Pentagon official said: "This attack took place in an area where the Syrian president does not have control."

Initial assessments found the attack was likely to be the work of the Islamic State group.

Syria recently became the 90th country to join an international coalition to combat the Islamic State.

US President Donald Trump met with his Syrian counterpart, Ahmed al-Sharaa, at the White House earlier this year.

The meeting between the two leaders saw them discuss bilateral relations, the toppling of the Islamic State, and regional issues.

"We want to see Syria become a country that’s very successful, and we think this leader can do it," Trump told reporters.