​Armed with U.S. weapons, infamous militia beating ISIS

AL MUQDADIYAH, Iraq - In Al Muqdadiyah they're celebrating victory over ISIS.

"Run away ISIS, we'll crush you," the soldiers chanted, a week after they drove out the extremists.

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The Badr Brigade chants as they celebrate a recent victory against ISIS
CBS News

But these soldiers are not part of Iraq's National Army. Instead, they're volunteers with a Shiite Muslim militia known as the Badr Brigade.

"Our guns all come from the Iraqi Defense Ministry," said Badr Brigade Commander Essam Yahya Hussein, who ran a grocery store before he joined the fight six months ago.

The U.S. spent $20 billion training and arming the Iraqi army. Now many of its weapons are in the hands of these unchecked militiamen.

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CBS News correspondent Holly Williams
CBS News

But with the Iraqi army in disarray, they have the best track record of defeating ISIS in central Iraq. The villages around Al Muqdadiyah are battle scarred and the local people have all fled. The battle for Al Muqdadiyah lasted four days, and when ISIS was finally defeated its fighters fled over hills where they've now regrouped.

The Badr Brigade may be effective, but they were born of Iraq's bloody civil war and their notorious death squads are implicated in the torture and murder of thousands of Sunni Muslims.

Last week, they were accused of shooting more than 70 unarmed Sunni men in Al Muqdadiyah- a video appears to show the aftermath.

"It's not true," said the militia leader when we asked him about the alleged massacre. "The civilians are our brothers."

Despite their murky past the Badr Brigades are being given unprecedented power by Iraq's Shiite dominated government. General Ali Al-Wazir commands the Iraqi Army's 20th Battalion, but now he and his men - along with their American weapons and equipment - have been put under the command of the leader of the Badr Brigade.

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General Ali Al-Wazir walks with CBS News correspondent Holly Williams
CBS News

"But you're national army and he's part of the Badr organization," I said.

"He was given the job by the prime minister," General Al-Wazi told me. "Everybody knows it."

As for Iran, its officials have admitted that their Quds special forces are fighting against ISIS in Iraq. That means, in Iraq, the U.S. is on the same side as both Badr - an infamously brutal militia - and Iran. It's a connection that shows just how complicated the battle against ISIS has become.