Reams of evidence of Iraqi security forces committing human rights abuses in the war against the Islamic State (ISIL) has led a key lawmaker to call on Washington to hold back some of its financial assistance to Baghdad.

Sen. Patrick Leahy (D-Vt.) said on Wednesday that the documentation–photographs and pictures that almost certainly show massacres of civilians, and executions and torture of prisoners carried out by Iraqi troops—demonstrates Iraqi “war crimes.”

“I would say that involves the Leahy Law,” he told ABC News, referring to a statue named after himself that forbids the US government from assisting foreign military entities that systematically commit human rights abuses. “And I’d argue that we should be withholding money.”

“I guarantee you ultimately we get blamed for it whether we did it or not,” he added.

According to ABC News, which broke the story on Tuesday, the Iraqi government is investigating the incidents, and the Pentagon claims to have “withheld assistance from certain Iraqi units on the basis of credible information in the past.”

But ABC News also reported that the government of Iraq decides how to allocate weapons donated by the US—a cache worth about $1 billion that includes 43,000 M4 rifles and other light infantry weapons.

It is also no secret that the Iraqi military has repeatedly committed human rights abuses with the assistance of American officials, after the US overthrew Saddam Hussein in 2003.

In the middle of last decade, as violence under the American occupation of Iraq reached a crescendo, American military advisers set up Special Police Commandos (SPC) that operated torture centers throughout the country. In interrogations, SPC officials would hang prisoners upside down, pull out their nails, and administer beatings and electric shocks in efforts to gather intelligence, The Guardian reported. James Coffman and James Steele–Pentagon officials who respectively answered directly to then-commander of US forces in Iraq Gen. David Petraeus and then-Defense Secretary Donald Rumsfeld—were well aware of the SPC activities, according to an Iraqi General who worked with them, Muntadher al-Samari. “They knew everything that was going on there,” al-Samari said. “The torture, the most horrible kinds of torture.”

In a June 2009 article in The Nation, Shane Bauer detailed how the Iraqi Special Operations Force, a contingent trained by the US army after April 2003, was accused of “human rights abuses, killings and politically motivated arrests…assaults on a university president and arrests of opposition politicians” in one part of Baghdad alone. The force was created to be accountable only to the office of the Iraqi Prime Minister, and although US relinquished direct control over it by June 2009, Bauer noted that “US Special Forces continue to ‘have advisers at every level of the chain of command. Many Iraqis in Baghdad, he reported, saw ISOF as “a covert, all-Iraqi branch of the US military.”

Both Iraqi police and ISOF units, through insignia, “are clearly identifiable in many of the photos and videos, which include many severed heads and corpses dragged behind humvees,” ABC News reported.

The latest round of ISIL-specific abuse allegations, too, have not exactly come out of left field. In early 2014, in what was termed an anti-ISIL operation, the Iraqi military killed hundreds and wounded hundreds more in a bombardment campaign in Fallujah. The shelling was described by at least two witnesses as “indiscriminate,” according to Truthout’s Dahr Jamail, who detailed how then-Iraqi Prime Minister Nour al-Maliki, a Shi’a, was seen by the city’s largely-Sunni population as a purveyor of sectarian violence. ISIL, Jamail reported in March, was at the time “not playing a significant role in the fighting in Fallujah.”

ABC News also noted in its Wednesday report that officials within the State Department and the military “had viewed examples of Iraqi Security Forces posting atrocities on personal social media for over a year.”

One anonymous official said that the abuses, however, have become “more severe” and “very concerning.” The matter, the official said, is “being raised at high levels in Baghdad.”

Read the ABC News report on “Dirty Brigades” here (warning: contains graphic images).