The United States said on Thursday that a base in Syria used by the US-led coalition was attacked with drones and artillery.
No US personnel were injured in the attack Wednesday at the Al-Tanf base, said Captain Bill Urban, a spokesman for CENTCOM.
"We can confirm that the Al-Tanf Garrison area was subjected to a deliberate and coordinated attack. Based on initial reports, the attack utilized both unmanned aerial systems and indirect fire," Urban said in a statement.
The attack was initially reported on Wednesday by the Britain-based Syrian Observatory for Human Rights.
The Al-Tanf base is a desert garrison in southern Syria set up in 2016 as part of the fight against the IS group.
Damascus and its allies have repeatedly said US troops had no reason to be there.