U.S. officials acknowledged Iranian-backed forces in Iraq could be using American-made arms, an admission that comes amid growing concern on Capitol Hill the U.S. government is quietly working with militia fighters in Iraq who are directly tied to the Islamic Revolutionary Guards Corps (IRGC), according to multiple sources familiar with the situation.

U.S. lawmakers and military insiders are concerned by what they described as the American government’s continued arming and training of Iranian-backed fighters in Iraq, an ongoing policy that multiple sources described to the Washington Free Beacon as one of the U.S.'s chief foreign policy failures in the region.

Top lawmakers and others have begun to present evidence showing that the State Department continues to provide widespread support for Iranian-backed militias in Iraq, a program that first begun under the Obama administration.

This has helped solidify Iran's presence in key Iraqi territories and appears to directly conflict with the Trump administration’s newly outlined push to combat the Islamic Republic's regional military efforts, which have included targeting U.S. forces in Syria and other locations.

Multiple sources who spoke to the Washington Free Beacon both on and off the record accused the State Department of making "common cause" with the IRGC, which they say has benefited from ongoing American efforts to arm and train Iraqi militia groups, many of which have direct ties to Iran.

These sources pointed to the continued presence of senior Obama administration officials in government as one of the primary drivers of this ongoing policy.

Senior Trump administration officials acknowledged they have seen evidence that some Iraqi forces on its blacklist are using American arms.

"We have seen reports that some U.S.-origin military equipment is being operated by Iraqi militia units that are not the approved end-users," said a spokesman for the White House National Security Council. "We urge the Government of Iraq to expeditiously return this equipment to the full control of the Iraqi Army."

However, the official said the United States has strict policies in place to prevent Iranian-tied forces and other terrorist actors from benefitting from its military programs in Iraq.

"All recipients of U.S. security assistance are fully vetted and subject to end-use requirements," the official said. "The United States has strict standards to avoid providing security assistance to designated terrorist organizations, units with close ties to Iran, or units under suspicion of committing gross violations of human rights."

Leaders on Capitol Hill are currently pushing the Trump State Department to come clean about possible interactions with Iranian-tied forces in Iraq.

Rep. Ron DeSantis (R., Fla.), a member of the House Foreign Affairs Committee, is one of several lawmakers who recently disclosed direct evidence of Iranian-backed fighters using American-made tanks and other military equipment in Iraq.

DeSantis told the Washington Free Beacon Congress is increasing pressure on the State Department to disclose currently withheld information on the relationship between the U.S. military and Iranian-backed militia groups in Iraq.

"The State Department should not be making common cause with the IRGC, [Iranian commander] Qassem Soleimeni, the [Iranian] Quds Force or Shia militias," DeSantis said, explaining that these groups have long worked to thwart U.S. operations in the region.

"These groups were responsible for killing hundreds of U.S. troops in Iraq during our operations there last decade," DeSantis said. "Congress needs to get the facts about the relationship between our own State Department and these nefarious actors."

Intelligence information circling around Capitol Hill and reviewed by the Washington Free Beacon shows that multiple IRGC proxy groups have been operating under the Iraqi Ministry of Interior (MOI), which coordinates and doles out U.S. funding and equipment to various militia groups.

Iranian-tied entities believed to be benefiting from U.S. programs include Kata’ib Hezbollah, an Iraqi Shia military group supported by Iran; and the Badr forces, an Iranian backed military group. At least four other Iranian-supported military groups also are said to have benefited from U.S. training programs, according to the intelligence information.

Photographs and other open-source intelligence information appear to show that Iraqi Prime Minister Haider al-Abadi is aware that Iran is cashing in on U.S. programs.

Al-Abadi's government is believed, in part, to allocate funds to these Iranian forces via Abu Mahdi al-Mohandes, a designated terrorist who leads Kata'ib Hezbollah, who then doles out U.S. funds to various Iranian-backed militia groups.

Kata'ib Hezbollah has been identified as receiving American funding, armor, and artillery via these programs.

Other photographic evidence in the possession of lawmakers appears to show various Iranian-backed militia fighters in Iraq using American-made M1A1 Abrams tanks, which require direct training from the United States to operate.

The State Department and Trump administration officials are said to be aware of this information, as well as other evidence, but stand accused of downplaying it so as not to interfere with the fight against ISIS in Iraq, which these Iranian militias have helped wage.

Bill Roggio, a veteran military analyst and editor of the Long War Journal, which chronicles U.S. military efforts, said the drive to defeat ISIS has pushed senior U.S. military and diplomatic officials to ignore Iran’s growing role in the Iraq.

"The U.S. military and government has been so desperate to defeat the Islamic State that it has consciously ignored that its allies in Iraq and Syria include Shia militias backed by Iran and the PKK [a Kurdish rebel group], which is designated by the U.S. government as foreign terrorist organization," Roggio said.

U.S. military officials who spoke to the Washington Free Beacon about the situation said that any concerns over the misuse of American-made arms are brought directly to the Iraqi government.

"If we receive reports that U.S.-origin equipment is being misused or provided to unauthorized users, we engage the Iraqi government in conjunction with the U.S. Embassy to address any confirmed issues—up to the highest levels, if necessary," one senior U.S. military official said. "That communication, however, is private."

The U.S. has "received assurances from the Government of Iraq and the Iraqi Security Forces that they will use U.S. equipment in accordance with U.S. law and our bilateral agreements," the official added.

Lawmakers and other have singled out Brett McGurk, the special presidential envoy for the Global Coalition to Counter ISIS, as playing a key role in enabling policies that help arm Iranian backed forces.

McGurk, who was also a senior official in the Obama administration, has long been viewed as a controversial figure due to his 2008 affair with a Wall Street Journal reporter while the two were in Iraq.

"The State Department continues to downplay the role of the IRGC militias, but they’ve literally hijacked the MOI [Ministry of Interior]," said Michael Pregent, a former intelligence official who has tracked U.S. aid to rogue militia groups. "The MOI receives U.S. funds and equipment, so what is the State Department doing about it? By not addressing it, they're putting Americans on the ground in danger."

One veteran congressional advisor who works closely with lawmakers on the Iran portfolio expressed concern the Trump administration is being led down the wrong foreign policy path.

"The Trump administration is supporting Iran in just about every country across the Middle East," the source said, expressing frustration about the policy on background because he is not authorized to speak on the record. "In the Gulf, the State Department is trying to get the Saudis to cave to Iran's Qatari allies. In Syria, the Defense Department is abandoning our allies. In Lebanon, they're bolstering the Hezbollah-controlled government. And in Iraq they're at-best incoherent because they continue to support Iran-controlled militias."

"That's what you get when you leave in place the Obama officials who originally orchestrated the pro-Iran pivot, like Brett McGurk," the source added. "The mystery is why the good people inside the administration, who come up to the Hill and tell lawmakers they don't want to see the Middle East controlled by Iran, don't do anything about it."

The State Department did not return a request for comment.