The US has carried out air strikes against Iran-backed militia groups in the Iraq-Syria border region.
Sunday’s strikes hit “operational and weapons storage facilities”, in response to drone attacks on US forces, the Pentagon said in a statement.
President Joe Biden would “act to protect US personnel”, it added.
The Pentagon did not provide any information on casualties. But a monitoring group reported that five militia fighters were killed in Syria.
The UK-based Syrian Observatory for Human Rights said several more fighters were wounded “in an attack by US warplanes”.
Syrian state news agency Sana meanwhile reported that a child had died and at least three other people were wounded.
This is the second round of air strikes President Biden has authorised against Iran-backed militias since taking office in January.
US forces based in Iraq have been targeted several times in recent months by drone attacks. Iran has denied any involvement.
About 2,500 US troops are based in the country as part of an international coalition fighting the jihadist Islamic State (IS) group.