Russia was given about four to five minutes warning of the Biden administration’s first military action when it struck Iranian-backed militias in eastern Syria early Friday, according to Russian Foreign Minister Sergei Lavrov. But he said the warning came too late to reduce the risk of a potential clash between the two country’s forces. U.S. officials believe the attack killed a number of alleged Iranian-linked fighters, signaling the administration’s intent to use targeted military action to push back against violence tied to Tehran.

The Britain-based Syrian Observatory for Human Rights reported Friday that 22 Iranian-backed fighters were killed when the strike at 1 a.m. local time Friday (6 p.m. Thursday in Washington) hit three truckloads of weapons crossing a border point from Iraq to Syria. It added that the death toll could rise.

Russia emerged as a key player in Syria when President Vladimir Putin deployed forces in 2015 to back Moscow’s longtime ally, President Bashar al-Assad. Russia claims to be the only foreign player legally in Syria, as Assad sought Russian help in confronting rebels in the country’s civil war.

Defense Secretary Lloyd Austin on Feb. 25 said he was confident the building targeted was used by the militia responsible for attacks against U.S. personnel. (AP)

Pentagon spokesman John Kirby said the attack hit facilities used by Iranian-linked Iraqi militias, including Kataib Hezbollah and Kataib Sayyid al-Shuhada, at a strategic border-crossing station in eastern Syria. The attack was “authorized in response to recent attacks against American and coalition personnel in Iraq, and to ongoing threats,” Kirby said.

Syrian state media confirmed the latest strike, reporting that it took place at a time when the army was targeting the Islamic State in the area.

Later Friday, Syria’s Foreign Ministry put out a statement condemning the attack, saying it breached international law and would escalate tensions in the area.