U.S. officials tell me they are seeing significant numbers of Iranian Revolutionary Guard Corps troops retreat from the Syrian combat zone in recent weeks, following the deaths and wounding of some of top officers in a campaign to retake Idlib Province and other areas lost this year to opposition forces supported by the West and Gulf Arab States. As a result, the Russian-initiated offensive that was launched in September seems to be losing an important ally.

On Friday at the Saban Forum at the Brookings Institution, Israeli Defense Minister Moshe Ya’alon said that Russia’s initial plan was to take back Idlib and other cities that had fallen under rebel control within three months. “It’s not going to happen because of the military difficulties,” he said, adding that the campaign to date looked to be a “failure.” He cited the “incompetence” of Syria’s army as well as “the lack of determination of the Iranian Revolutionary Guard Corps.”

This is a surprising turn of events. A number of Western media outlets reported this fall that Qassem Suleimani, the leader of Iran’s elite Quds Force, and Russia’s defense ministry had negotiated an infusion of Iranian forces into Syria over the summer, shortly after the conclusion of the nuclear negotiations between Iran and six other world powers. That surge was supposed to change the tide of the Syrian war that the dictator Bashar al-Assad was losing, as more of his territory fell to a coalition of rebels supported by the U.S., Saudi Arabia, Qatar and others.