The US military carried out air strikes on Tuesday in Syria against facilities used by groups affiliated with Iran's Revolutionary Guards Corps (IRGC).
The strikes in Deir al-Zor area came even as the United States aimed to respond to a draft agreement proposed by the European Union that would bring back the 2015 nuclear deal with Iran that former President Donald Trump abandoned, and current President Joe Biden has sought to revive.
The military's Central Command said in a statement that such strikes were aimed at protecting US forces from attack by Iran-backed groups.
Iran has so far not commented on the attack and government-controlled media did not report the development on Wednesday.
It cited one such incident on Aug. 15, which Reuters has reported involved drone attack on a compound run by coalition and US-backed Syrian opposition fighters, with no casualties.
Reports say the US will likely respond to the EU proposal on the nuclear talks on Wednesday, most probably followed by more indirect negotiations with Iran to resolve all differences.
The agreement is strictly about restricting Iran’s nuclear program in exchange for US sanctions relief and does not cover other issues, such as Iran’s aggressive activities in the region or its missile program.
The Biden Administration has refused to lift sanctions imposed in 2019 on the IRGC for its “malign activities” and support for proxy groups in the Middle East as part of the nuclear deal.
"The president gave the direction for these strikes," said spokesman Army Colonel Joe Buccino.
Central Command called the strikes a "proportionate, deliberate action intended to limit the risk of escalation and minimize the risk of casualties."
The statement about Tuesday's US strike did not mention whether there were any casualties and did not say whether the air strikes were carried out by manned or unmanned aircraft.
This is not the first time US warplanes have struck Iran-backed forces in Iraq and Syria. The United States hit operational and weapons storage facilities at two locations in Syria and one in Iraq in June last year.
US forces first deployed into Syria during the Obama's administration's campaign against Islamic State, partnering with a Kurdish-led group called the Syrian Democratic Forces. There are about 900 U.S. troops in Syria, most of them in the east.
But Iran-backed militias established a foothold in Syria while fighting in support of President Bashar al-Assad during Syria's civil war.
Iranian-backed militias are heavily concentrated west of the Euphrates in Deir al-Zor province, where they get supplies from Iraq through the al-Bukamal border crossing.
Israel, which strongly oppose the Iranian presence in Syria, has launched hundreds of airstrikes against Iranian positions and those of its allies in Syria.
An IRGC general was killed in Syria last week, reportedly in the latest airstrike carried out against Iranian bases.
With reporting by Reuters