Central Command says the raids on Deir Az Zor were aimed at protecting US forces from attack by Iran-linked groups.
The United States says it has carried out air raids in eastern Syria, targeting infrastructure facilities used by groups affiliated with Iran’s elite Revolutionary Guards Corps (IRGC).
In a statement on Wednesday, the US military’s Central Command said the raids in Syria’s Deir Az Zor were ordered by President Joe Biden.
Iran denied any links to the fighters, and there was no immediate comment from Syria’s government.
The Syrian Observatory for Human Rights, an opposition war monitor, said that the raids had targeted the Ayash Camp run by the Fatimiyoun group, mainly made up of Iran-backed Shia fighters from Afghanistan.
The monitor said that at least six Syrian and foreign fighters were killed in the attack.
The Central Command said the raids “took proportionate, deliberate action intended to limit the risk of escalation and minimize the risk of casualties”.
It did not identify the targets nor offer any casualty figures from the attacks.
“Today’s strikes were necessary to protect and defend US personnel,” Central Command Spokesperson Colonel Joe Buccino said in the statement.
The colonel added the attack was in response to an August 15 attack targeting US forces.
That attack saw drones allegedly launched by Iranian-backed militias target the al-Tanf Garrison used by US forces. The Central Command described the assault as causing “zero casualties and no damage” at the time.
Iran’s foreign ministry condemned Wednesday’s raids as a “violation by the US army of the people and infrastructures of Syria”, which it said also amounted to a violation of the country’s territorial integrity and independence.
In a short statement, foreign ministry spokesman Nasser Kanani condemned the “terrorist move” against unnamed fighter groups that he denied had any links with Iran.
“Continued US military presence in parts of Syrian soil runs counter to international law and is a violation of the country’s sovereignty, which constitutes occupation,” Kanani said, calling on Washington to leave Syrian soil, stop “plundering” its oil and grain, and refrain from using combating “terrorism” as an excuse to remain in the country.
Deir Az Zor is a strategic province that borders Iraq and contains oil fields.
Iran-backed militia groups and Syrian forces control the area and have often been the target of Israeli warplanes in previous raids.
US forces entered Syria in 2015, backing allied forces in their fight against the ISIL (ISIS) group.