On Oct. 22, a team of Kurdish soldiers, backed up by elite commandos from the U.S. Army’s Delta Force, raided an ISIS prison compound in the Iraqi town of Hawija, where Kurdish intelligence indicated dozens of their own peshmerga fighters were being held. It turned out there were no Kurds in the prison, but 69 hostages were freed, and more than 20 ISIS fighters were killed.

The Kurds also took six ISIS fighters as their prisoners. And now, U.S. officials and humanitarian aid workers in the region tell The Daily Beast, it appears those prisoners are being tortured in Kurdish custody, in violation of international law.

“I am sure they are being tortured, no question,” said a U.S. defense official in Iraq who is familiar with the raid and spoke on the condition of anonymity. He noted that Americans do not have access to them, but added, “You have to remember where we are. Torture is pervasive.”

The brutality of the Kurdish campaign against the so-called Islamic State widely known as ISIS is well established in reporting by The Daily Beast and other media. But the treatment of these prisoners, taken with the assistance of U.S. government forces who then deny any responsibility for what happens to them, is reminiscent of the “rendition” program under Presidents Bill Clinton and George W. Bush, which transferred suspected terrorists to the custody of governments that used methods of torture flatly prohibited by American and international law.

A human-rights worker in the region, who asked not to be identified, said Kurdish authorities haven’t disclosed where the prisoners are being held and that he, too, thinks that is because the prisoners are being tortured.

Various nongovernmental organizations in Iraq and Syria have documented, over the course of the U.S.-led war against ISIS, systematic abuses by Kurdish military forces against the militants and their perceived sympathizers, including the forced removal of civilians from their homes in what one human-rights group said amounted to “war crimes.”

But U.S. officials told The Daily Beast that Washington hasn’t asked the Kurds for access to the ISIS prisoners, and the U.S. defense official in Iraq said he doesn’t believe the U.S. military has formally raised the issue with the Kurds, either.

The fate of a handful of ISIS fighters “is low on our priority list,” the defense official said.

Few tears may be shed at the thought of ISIS fighters—who celebrate the beheading, burning, and drowning of their own captives—suffering cruel treatment at the hands of Kurdish forces, who have provided a crucial and effective ground force to complement U.S.-led airstrikes against ISIS in Iraq and Syria.

But the abuse of ISIS prisoners could become a propaganda instrument for the militants, and further their own twisted justification for harming their captives.

While U.S. officials have stressed that the raid in Hawija that netted the six ISIS fighters was a Kurdish operation, the mistreatment of those prisoners would inevitably be linked to the United States government and the military, which was present at the raid and provided air support.

Indeed, ISIS has already made a propaganda point by using some of the CIA’s own interrogation techniques, which President Obama called “torture,” on its own hostages. Before beheading American journalist James Foley in 2014, his ISIS jailers subjected him to waterboarding, a form of near-death drowning that the CIA used on al Qaeda detainees.

ISIS also dresses its hostages in orange jumpsuits meant to mimic those worn by U.S. detainees at Guantanamo Bay, Cuba. The abuse of prisoners by the U.S. military and intelligence operatives has become a potent instrument for ISIS and other jihadist groups campaigning to win recruits.

Under international law, the International Committee of the Red Cross (ICRC) is supposed to be granted access to prisoners and detainees to ensure they’re treated humanely and not tortured. But it’s not clear that has happened in the case of the six ISIS fighters.

A spokesperson for the Kurdistan Region Security Council, which oversaw the raid and helps coordinate U.S.-led airstrikes against ISIS forces, told The Daily Beast, “These individuals are being held in Kurdistan and are still being processed.” It’s been a month of processing, apparently.

Asked if the prisoners had been given access to the International Committee for the Red Cross and were being treated humanely, he said, “ICRC has access to all ISIS prisoners in the Kurdistan region, and yes they are afforded with the care afforded to them by local and international law.”

But that claim is nearly impossible to verify because the ICRC will not confirm or deny that it has been given access to the prisoners.

As a matter of policy, the ICRC doesn’t publicly comment on its access to prisoners and detainees, and a spokesperson for the group declined to do so for this article.

“As part of its neutral and humanitarian role, the ICRC seeks to gain access and visit all persons detained in connection with an armed conflict in order to monitor their conditions of detention and treatment, as well as to help them establish links with their families,” Trevor Keck, the deputy spokesperson for the group’s Washington delegation, told The Daily Beast.

“The ICRC in Iraq visits over 40,000 detainees in over 60 places of detention every year,” Keck continued. “In accordance with our confidential working method, which relies first and foremost on confidential, bilateral dialogue with the concerned authorities, we do not comment on the cases of specific detainees.”

However, the group has been granted access to an ISIS prisoner before, a fact that was publicly disclosed at the time by the Obama administration. When U.S. special operations forces raided the home of a top ISIS figure, Abu Sayyaf, in Syria last May, they killed him but captured his wife. The woman known as Umm Sayyaf, an Iraqi citizen, was held in U.S. military detention in Iraq, and representaives from the ICRC were allowed to meet with her.

At the time of her capture, officials told The Daily Beast that the woman was providing valuable intelligence about ISIS’s inner workings, including its enslavement and sexual abuse of women.

But then, in August, the U.S. transferred Umm Sayyaf into Kurdish custody. That raised concerns that she could be mistreated, particularly in light of a lengthy report by Human Rights Watch that women in the Iraqi criminal justice system are routinely abused and denied due process.

At the time of Umm Sayyaf’s transfer, experts questioned whether the U.S. was setting a dangerous precedent by transferring detainees to Iraqi or Kurdish authorities rather than keeping them in American hands, where they’d undoubtedly see better treatment but would also become the legal responsibility of U.S. authorities.

The Geneva Conventions keep belligerents in a conflict from transferring a detainee to another power when it won’t apply the conventions, which include protections against torture.

“Any ISIS detainees who were involved in torturing or summarily executing the hostages should be investigated and prosecuted for war crimes,” said Jonathan Horowitz, a legal officer with the Open Society Justice Initiative. “By the same token, if Kurdish forces are torturing those same ISIS detainees, then that’s a war crime, too,” he told The Daily Beast. “Torture is banned in every and all circumstances, regardless of who the prisoner is and what he’s accused of.”

“At a minimum,” Horowitz continued, “the U.S. should raise serious concerns about the torture allegations.” He added that the U.S. also “needs to ensure it won’t participate in future operations that it knows are likely to result in abuses as serious as torture.

But in the case of the ISIS fighters captured at the prison in Hawija, the U.S. says it wasn’t in control of the prisoners at all.

“They were never ours,” one U.S. military official told The Daily Beast, noting that the fighters were taken into custody by Kurdish forces in a Kurdish-led operation.

A senior Obama administration official told The Daily Beast, “We are not aware of information suggesting that these ISIL prisoners have been mistreated in detention in Iraqi Kurdistan,” using an alternate acronym for the group. “However, we take all such allegations seriously, and we fully expect that our Kurdish partners will continue to adhere to international standards and norms for detainees.”

The U.S. may not have an affirmative obligation to ensure that the prisoners are treated humanely, since it wasn’t in the lead. But the U.S. presence and participation in the raid was undeniable. In addition to ground forces, the military provided transport helicopters, and a U.S. jet later bombed the prison, destroying it. One American soldier, Army Master Sgt. Joshua Wheeler, was killed in the raid. He was buried last week in Arlington National Cemetery.

For the U.S. military, the best way to use its leverage with the Kurds may not be to address the treatment of ISIS prisoners. Rather, the United States has been urging the Kurds to conduct themselves professionally when liberating towns, particularly Arab-dominated ones, amid reports Kurdish forces have looted from and beaten Arab residents.

Throughout the course of the U.S-led campaign against ISIS, human-rights groups have documented a pattern of Kurdish forces abusing civilians in towns in Iraq and Syria that they captured from ISIS.

In northern Iraq, Kurdish forces have destroyed dozens of Arab homes and confined thousands of Arab residents to so-called security zones. They are forbidden from returning to their homes, although in some cases Kurds are allowed to move in, Human Rights Watch said in a report in February.

“Cordoning off Arab residents and refusing to let them return home appears to go well beyond a reasonable security response to the ISIS threat,” Letta Tayler, the senior terrorism and counterterrorism researcher at Human Rights Watch, said at the time. “The U.S. and other countries arming the Iraqi Kurdish forces should make clear that they won’t stand for discrimination under the guise of countering terrorism.”

The group said it found no evidence of Kurdish forces imposing similar restrictions on Kurds. Human Rights Watch raised its concerns with Kurdish authorities, who eased some of those restrictions, the group said.

But in neighboring Syria, the same kinds of abuses have continued.

During a fact-finding mission in northern Syria last summer, Amnesty International uncovered what it described as “a wave of forced displacement and home demolitions” by Syrian Kurdish forces in control of the area.

The group accused the forces of razing whole villages, often in retaliation for the residents’ perceived sympathies with or ties to ISIS and other militants. The majority of the civilians are Arabs and Turkmen, but Kurds have also been moved out of their homes.

The Syrian Kurdish political party in charge of the semi-autonomous region where the displacement took place “is abusing its authority and brazenly flouting international humanitarian law, in attacks that amount to war crimes,” Lama Fakih, the senior crisis advisor at Amnesty International, said in a report in October.

“We saw extensive displacement and destruction that did not occur as a result of fighting. This report uncovers clear evidence of a deliberate, coordinated campaign of collective punishment of civilians in villages previously captured by [ISIS], or where a small minority were suspected of supporting the group,” Fakih said.

“They pulled us out of our homes and began burning the home… they brought the bulldozers,” one resident told Amnesty International investigators. “They demolished home after home until the entire village was destroyed,” said another witness.

Most residents claimed that while ISIS sympathizers had lived in some villages, the majority of residents were opposed to the group, according to Amnesty International. Kurdish forces told Amnesty investigators that the civilians were being moved for their own protection, the group reported.

But some civilians also said the Kurdish forces had threatened them with airstrikes by the U.S.-led coalition if they failed to leave their homes.

“It is critical that the U.S.-led coalition fighting [ISIS] in Syria… do not turn a blind eye to such abuses,” Fakih said.

But in a brutal war with brutal allies, Washington may well have decided to see no evil.