Iranian militants have begun acting as Russia’s de facto “ground force” in Syria, where they have begun waging “an ethnic cleansing campaign” in order to eradicate opposition to the embattled President Bashar al-Assad, according to leading members of Congress, defense officials, and outside experts.

A Pentagon official who was not authorized to speak on the record confirmed to the Washington Free Beacon that the United States “continue[s] to see Iranian-sponsored forces providing support to the Syrian regime in their fight against Syrian opposition forces.”

It is now believed that Iranian Revolutionary Guard Corps forces are acting as Russia’s “ground force” in Syria, helping Moscow to clear out primarily secular opposition forces battling to depose Assad, according to lawmakers and regional experts.

Both Russia and Iran have tried to avoid battling Islamic State militants in the country despite repeated claims otherwise, these sources said.