The US military's Central Command said it is investigating whether there were civilian casualties in the drone strike that killed an Al Qaeda leader in Syria's north-western region of Idlib on Friday.
“We abhor the loss of innocent life and take all possible measures to prevent them,” Centcom spokesman Capt Bill Urban said.
“The possibility of a civilian casualty was immediately self-reported to US Central Command. We are initiating a full investigation of the allegations and will release the results when appropriate.”
Centcom said the attack was conducted by an MQ-9 Reaper drone, but did not identify the Al Qaeda leader targeted in the strike, or say how many civilians are suspected to have been killed.
In late October, the US military said it had killed another Al Qaeda leader, Abdul Hamid Al Matar, in a drone strike in north-west Syria, but there were no indications of civilian casualties.
Centcom announced the killing another Al Qaeda member, Salim Abu Ahmad, in a similar attack in September.
“Al Qaeda continues to present a threat to America and our allies,” the US Army's Maj John Rigsbee said after the attack on Al Matar.
“The removal of this Al Qaeda senior leader will disrupt the terrorist organisation's ability to further plot and carry out global attacks threatening US citizens, our partners, and innocent civilians.”
Two days before the announcement of Al Matar's death, US officials said an American outpost in southern Syria's Al Tanf came under attack but resulted in no casualties.
Al Tanf is in a strategic area near the Syrian border crossings with Iraq and Jordan.
Syria's last major rebel bastion, Idlib has been under the control of a militia umbrella group known as Hayat Tahrir Al Sham, which has links to Al Qaeda’s branch in Syria.
The Idlib region is home to nearly three million people, two thirds of them displaced from other parts of the country during the decade-old civil war.