U.S. Troops Join Assault on Prison Where ISIS Holds Hostage Hundreds of Boys

American ground forces have joined the fight to retake control of a prison in northeast Syria where Islamic State fighters are holding hundreds of boys hostage, the Pentagon said Monday.

After four days of American airstrikes, the fight has become the biggest known American engagement with ISIS since the fall of its so-called caliphate three years ago.

Hundreds of Islamic State fighters attacked the makeshift prison in Hasaka, Syria, on Friday in an effort to free their detained comrades in one of the boldest attacks by the group in the region in recent years.

The siege of the prison, which houses about 3,000 suspected ISIS fighters and almost 700 boys, has evolved into a hostage crisis with ISIS fighters still holding about a quarter of the prison and using the boys as human shields.

The overcrowded, makeshift prison has long been an avowed target for a resurgent Islamic State. Housed in a converted technical college, it is the largest of several prisons in the region holding thousands of fighters detained after the territorial defeat of ISIS in 2019.

The American-backed force overseeing the prison, the Syrian Democratic Forces, has complained for years that it lacked the ability to operate it securely.

The S.D.F. said that it had recaptured one of the prison’s three buildings in a dawn raid on Monday.

An S.D.F. spokesman said about 300 Islamic State fighters had surrendered but that ISIS had threatened to kill the boys if the coalition continued its assault on the prison.

 “We have some reports saying that ISIS is threatening to kill all the minors if we continue attacking them,” the spokesman, Farhad Shami, said.

The aid group Save the Children said it could not independently confirm the casualties but had received audio testimony indicating deaths and injuries among the children.

In a voice recording obtained by Human Rights Watch on Sunday, a boy who identified himself as a 17-year-old Australian said he had been wounded in an airstrike but there was no medical care available.

The Pentagon said that the coalition had moved in armored Bradley fighting vehicles to back the S.D.F. forces, indicating for the first time that U.S. ground forces were involved in the fight. A coalition official said the vehicles had been fired at and had returned fire.

“We have provided limited ground support, strategically positioned to assist security in the area,” John F. Kirby, the Pentagon spokesman, told reporters in Washington. U.S. military officials said the Bradleys were being used as barricades while the S.D.F. tightened its cordon around the prison.

The United States has also carried out airstrikes with Apache helicopter gunships over the past four days to try to break the siege, killing an unknown number of prisoners.

The U.S. troops are part of a residual force of the American-led military coalition that was kept in Syria to assist in the fight against ISIS and to protect oil installations. There are currently about 700 American troops in northeast Syria, operating mostly from a base in Hasaka, and another 200 near Syria’s border with Jordan.

Mr. Shami said that 30 S.D.F. fighters had been killed in the operation to take back the prison, and that about 200 ISIS fighters and inmates who joined them in an attempt to escape had been killed since Friday. It was not clear how many prisoners had escaped.

The siege of the Sinaa prison in Hasaka demonstrated that the Islamic State still had the ability to mount a coordinated military operation, despite its territorial defeat by the U.S.-led coalition and Kurdish-led forces three years ago.

It has also highlighted the plight of thousands of foreign children brought to the ISIS caliphate in Syria by their parents, who have been detained for three years in camps and prisons in northeastern Syria, and abandoned by their own countries.

The inmates in Hasaka include boys as young as 12, including Syrians, Iraqis and about 150 non-Arab foreigners. Some had been transferred to the prison after they were deemed too old to remain in detention camps that held families of Islamic State suspects.

The Syria director for Save the Children, Sonia Khush, said those holding the children were responsible for their safety. But she also blamed the foreign governments for not repatriating their detained citizens and their children.

“Responsibility for anything that happens to these children also lies at the door of foreign governments who have thought that they can simply abandon their child nationals in Syria,” Ms. Khush said. “Risk of death or injury is directly linked to these governments’ refusal to take them home.”

At its peak, the Islamic State held territory the size of Britain straddling Iraq and Syria. An estimated 40,000 foreigners, including children, made their way to Syria to fight or work for the caliphate.

Thousands of them brought their young children — too young to understand and much too young to make a choice. Other children were born there.

When the last piece of the ISIS caliphate in Baghuz, Syria, fell three years ago, surviving women and young children were put in detention camps while suspected fighters and boys as young as 10 were sent to prison.

The main detention camp for ISIS families, Al Hol, is squalid, overcrowded and dangerous, with not enough food or medical services, not enough guards and an increasingly radicalized segment of detainees who terrorize other camp residents.

When the boys at the camps become teenagers, they are usually transferred to Sinaa prison in Hasaka.

Detainees there, including minors, are packed into overcrowded cells without access to sunlight. There is insufficient food and little medical care, according to prison guards in the impoverished breakaway region of Syria known as Rojava.

When they reach age 18, the youths are placed with the general prison population, where wounded ISIS fighters sleep three to a bed. None of the non-Syrian detainees have been charged with a crime or gone to trial.

While Rojava authorities run a rehabilitation center, it has space for only about 150 detainees. When they finish the course, the Syrians are released but the non-Syrians are returned to prison.

“We help them to construct their prisons, to train their staff, to run as good a prison system as they can, but they are not getting what they need,” said Anne Speckhard, director of the International Center for the Study of Violent Extremism. “Prisoners are lying on top of each other.”

Thousands of ISIS recruits came from Europe, but most European countries, citing security concerns, have refused to repatriate their citizens, apart from orphans. Some have stripped their nationals detained in Syria of citizenship for joining ISIS.

“As long as it stays over here that’s what everybody wants,” Ms. Speckhard said of countries refusing to repatriate their citizens. “‘We don’t want it to come over here.’”

Rights activists have compared the prison to the U.S. detention center in Guantánamo Bay, Cuba, as a place where suspects can be warehoused and forgotten.

The State Department said Monday that the siege highlighted the need for international financial support to improve security at the prison.

“It also underscores the urgent need for countries of origin to repatriate, rehabilitate, reintegrate and prosecute, where appropriate, their nationals detained in northeast Syria,” the State Department’s statement said.