A war monitoring group said on Tuesday that unidentified drones struck Iranian-backed militia vehicles while they crossed into Syria from Iraq through al-Bukamal.

There were unconfirmed reports of casualties.

Al-Bukamal is the Syrian city that controls the border checkpoint on the main Baghdad-Damascus highway. The highway is part of the main overground supply route linking Iran to its proxy fighters in Syria and Lebanon.

The Syrian Observatory for Human Rights, a Britain-based organization that monitors the war, said blasts were heard in Deir al Zor, where Iranian-backed militias and Iran’s Revolutionary Guards fighters have a heavy presence.

The US rejected having conducted the airstrike. “We can confirm these are not our airstrikes,” a CENTCOM official told Al Arabiya English.

Israel did not comment on the report. However, Tel Aviv rarely comments on its strikes in Syria.

Last January, Israel said it had hit about 50 targets in Syria in 2020.

The Israeli army has carried out hundreds of air and missile strikes on Syria since the civil war broke out in 2011, targeting Iranian and Lebanese Hezbollah forces as well as government troops.