US officials: Up to 100,000 Iran-backed fighters now in Iraq

As many as 100,000 Iranian-backed Shiite militia are now fighting on the ground in Iraq, according to U.S. military officials — raising concerns that should the Islamic State be defeated, it may only be replaced by another anti-American force that fuels further sectarian violence in the region.

The ranks have swelled inside a network of Shiite militias known as the Popular Mobilization Forces. Since the rise of Sunni-dominated ISIS fighters inside Iraq more than two years ago, the Shiite forces have grown to 100,000 fighters, Col. Chris Garver, a Baghdad-based U.S. military spokesman, confirmed in an email to Fox News. The fighters are mostly Iraqis.