Air strikes have hit positions of Iran-backed forces and allied militias in eastern Syria, killing 18 fighters, according to a group monitoring the war.
The Britain-based Syrian Observatory for Human Rights said on September 9 that the overnight raids carried out by unidentified warplanes took place in the region of Al-Bukamal near the Iraqi border.
The Observatory said the strikes targeted posts, military vehicles, and arms depots, causing extensive damage.
The number of deaths was likely to increase, it said.
A local activist collective in eastern Syria, the Sound and Pictures, also reported the air strikes, saying they hit an arms depot for Iraq's Popular Mobilization Forces, a grouping of mostly Iran-backed Shi’ite militias.
Also on Monday the Israeli military said Iranian-backed Shi'ite militias fired rockets at Israel from Syria on Monday but they fell short.
"A number of rockets were launched by Shi'ite militias operating under the command of the Iranian Qods Force from Syrian territory near Damascus," the military said, referring to the extraterritorial arm of Iran's Revolutionary Guards.
Israel views Iran as its greatest threat and has allegedly struck Iran-linked targets in Syria, Iraq, and Lebanon in recent weeks.
Iran, along with Russia, has given President Bashar al-Assad crucial backing throughout the Syrian war that began with a government crackdown on protesters in March 2011.