Hundreds of Iranian troops, already on the ground in Syria, are readying to battle against anti-government rebel forces in a drive to recapture territory for Syrian President Bashar Assad.
The soldiers entered Syria 10 days ago, Reuters reported on Thursday, citing Lebanese sources.
The Lebanese-based terror group Hezbollah was also poised to join the offensive alongside the regular Syrian army. The offensive is planned for an area in northern Syria.
Russian jets recently deployed in Syria, which began bombing targets on Wednesday, were to provide air cover for the operation.
“The (Russian) air strikes will in the near future be accompanied by ground advance by the Syrian army and its allies,” the sources said.
According to a report from the Telegraph, the Russian Defense Ministry said on Thursday that it does not differentiate between the extremist Islamic State group in Syria and rebel forces battling to end Assad’s rule, apparently confirming Western suspicions that the Russian airstrikes were not confined to IS positions.
US Defense Secretary Ashton Carter said the Russians appeared to have targeted areas that did not include IS militants and complained Moscow did not use formal channels to give advance notice of its airstrikes to Washington, which is conducting its own airstrikes in Syria against the Islamic State group.
AP contributed to this report.