Kata’ib Hezbollah, an Iranian-supported Iraqi militia group, has threatened to “fight American occupiers” and accused U.S. troops of aiding the Islamic Statein Iraq. “Washington is engaged in smuggling and evacuating Islamic State criminals from Iraq,” Jafar al-Husseini, the spokesman of the group, was quoted as saying in an article published on the organization’s official website. It added that the group will release evidence to substantiate the allegations in the future. “These criminal trafficking operations are conducted through the [Iraqi] Kurdistan region as a starting point, and then to Turkey,” he added. Al-Husseini also warned that his forces oppose the presence of U.S. troops on the Iraqi soil and are ready to fight against them. “We are not students of war. We are ready to fight more than ever before. Our military capabilities are ten times what they were in the past,” he boasted. “The Iraqi people reject American presence on the Iraqi soil and the major violations committed during their occupation. Iraqis stand behind the Islamic resistance factions in the face of America’s presence,” he continued.

The militia commander also praised the latest territorial gains by pro-Syrian regime forces in Deir Ezzor Province, and opined that victories in Syria will have a positive impact on the Iraqi battlefield.

Comment: In the past one year, the U.S. and Iranian-backed forces have been de facto allies in Iraq. The Tal Afar operation was the latest example of the U.S.-led coalition and Iranian-backed groups fighting on the same side. However, as the common foe is ousted from its major Iraqi strongholds, including Mosul and Tal Afar, Iran’s Revolutionary Guards and its Iraqi proxies have dialed up propaganda against the U.S. and its regional allies – which poses risks to U.S. military advisers helping the Iraqi security forces and complicates stabilization efforts in the war-torn country.

Last month, an article in hardline Javan Online, an I.R.G.C. mouthpiece, said the liberation of Tal Afar is a “major defeat for America and terrorists” and paves the way for the expulsion of U.S. Troops from Iraq. “The biggest loser of the Tal Afar operation and this victory is the United States of America,” it added.

Tehran has also stepped up diplomatic pressure on Baghdad. When Iraqi Prime Minister Haider al-Abadi visited Tehran in June, Supreme Leader Ali Khamenei made two key propositions to him: to expel the U.S. forces and not to dissolve the P.M.F. after the Islamic State’s defeat. Many Iranian-backed P.M.F. groups have implicitly and explicitly threatened the U.S. forces in Iraq in recent months.

Kata'ib Hezbollah, or the Hezbollah Brigades, is an Iranian-sponsored Shiite militia group that operates both in Iraq and Syria. The group is a unit within Iraq’s Popular Mobilization Forces (P.M.F.), but it receives its instructions more from Tehran than Baghdad.

The group has a long history of committing acts of terrorism against U.S. forces in Iraq. In 2009, the U.S. Departments of Treasury and State designated Kata'ib Hezbollah as a terrorist entity for having “committed, directed, supported, or posed a significant risk of commit acts of violence against Coalition and Iraqi Security Forces.” In the wake of the 2003 Iraqi invasion, the group’s cell members carried out numerous attacks against U.S. forces. According to U.S. officials, Iran’s elite Quds Force funded and trained members of the group jointly with the Lebanese Hezbollah.