U.S.-Backed Forces Struggle to Contain Islamic State in Battle Over Syrian Prison

Syrian fighters backed by American airstrikes struggled to retake control of a prison attacked by Islamic State in northeastern Syria on Sunday, as the militant group’s attempt to replenish its ranks with freed prisoners sparked the area’s worst sustained fighting in years.

The prison attack, which began last week, was one of the most complex and brazen Islamic State operations in Syria and Iraq in the past three years. It involved sleeper cells, suicide bombers and an insurrection inside the prison, said the Syrian Democratic Forces, the U.S.-backed, Kurdish-led militia that controls a section of northeastern Syria that is autonomous from the regime in Damascus.

The assault represents an attempt to boost the morale of Islamic State followers by returning to one of its original tactics: freeing members held in prison. Islamic State has struggled to survive as an underground militant group since it lost control of its territorial empire in 2019 following years of Iraqi, Syrian and American military operations.

The fighting has centered on a prison in the city of Hasakah about 50 miles south of the Turkish border. The Thursday night attack triggered days of street-by-street gunbattles in a poor civilian neighborhood as members of the SDF attempted to retake the area.

The SDF said it had killed 112 Islamic State fighters and prison rioters since the attack began, releasing video footage that it said showed the bodies of gun-wielding militants laid out in the streets next to bullet-ridden cars.

Islamic State said it freed 800 prisoners in the attack but provided no evidence to support the claim. The SDF also denied the assertion.

“It is impossible for 800 people to leave the area when we have it under a security cordon,” said Matay Hanna, a spokesman for the Syriac Military Council, one of the military units that make up the SDF.

On Sunday, the SDF was still trying to clear out Islamic State militants hiding among civilians, said Mr. Hanna.

“Our objective goes beyond killing ISIS; we are trying to arrest them and this is affecting the speed of operations,” he said. “They are within [civilian] areas, and they have killed civilians and are holding others hostage. We are working with our people to pull them out.”

Islamic State also released a video showing its militants standing over people it captured inside the prison, identifying them as SDF fighters. The SDF said the captives were prison kitchen staff.

The Pentagon said the U.S. carried out airstrikes in support of the SDF’s efforts to reassert control in Hasakah. The American-led military coalition against Islamic State said the strikes continued throughout the dayslong operation, with U.S.-led forces also providing real-time surveillance and other backing to SDF forces on the ground.

The prison break has also become one of the most serious challenges in years to the SDF, which controls northeast Syria with the backing of about 900 U.S. soldiers. An aborted decision by the Trump administration to withdraw American forces from the country in 2019 has raised questions about the future of the U.S. military footprint in the area.

“The fact that the SDF’s ability to keep a lid on ISIS is directly linked to an unpredictable U.S. presence in Syria is one of the biggest challenges facing the northeast,” said Dareen Khalifa, a senior Syria analyst at International Crisis Group.

Prison breaks have been one of Islamic State’s essential methods of building up its forces, helping the group transform into a potent army after its origins as an insurgency against U.S. forces in Iraq following the 2003 invasion.

A large prison break in Iraq in 2013 freed hundreds of inmates, swelling the ranks of what was then known as Islamic State in Iraq, immediately before the group’s rise as a major conventional fighting force that swept across Syria and Iraq.

Former Islamic State leader Abu Bakr Baghdadi called for more prison breaks in one of his last public statements before he was killed in a U.S. airstrike in 2019. In a recording attributed to him, Baghdadi urged his followers to free “soldiers of the caliphate” from prisons.  

The SDF runs prisons that hold thousands of suspected Islamic State members and oversees displacement camps for tens of thousands of the militants’ wives, children and other family. They include numerous foreign nationals from Europe, Asia and the Middle East. Local Syrian officials have warned that the camps have provided a recruiting ground for the extremists and have asked foreign countries to take their citizens back. Few countries have agreed to accept the return of their citizens, leaving them in limbo in Syria.

The SDF said it had killed Iraqi and Chinese nationals as it battled to retake the prison in Hasakah.

“While it remains militarily defeated, Daesh remains an existential threat to the region. Due to its severely downgraded capability, Daesh’s future survival is dependent on its ability to refill its ranks through poorly-conceived attempts like the Hasakah attack,” said Maj. Gen. John W. Brennan, Jr., the commander of the U.S.-led coalition fighting Islamic State, using the group’s Arabic acronym.

Attacking the detention facility had been a priority for Islamic State for more than a year, the State Department said.

“It also underscores the urgent need for countries of origin to repatriate, rehabilitate, reintegrate, and prosecute, where appropriate, their nationals detained in northeast Syria,” said State Department spokesman Ned Price on Saturday.