The new estimate compounds the challenge of relocating the captured Islamic State fighters to their home countries and makes it harder for the US-led coalition to wind down operations in Syria, even after the extremists no longer hold territory.
US-backed forces in Syria are holding more than 2,000 suspected Islamic State fighters, US defence officials said, at least double previous estimates and an obstacle to Trump administration plans to withdraw American forces from Syria, Dow Jones Newswires reported in an article provided to EFE on Wednesday.
The new estimate compounds the challenge of relocating the captured Islamic State fighters to their home countries and makes it harder for the US-led coalition to wind down operations in Syria, even after the extremists no longer hold territory. The development puts a greater burden on the US, which now may have to help US-allied forces detain the captured Islamic State fighters or prepare them for release.
The US military estimated last fall that the American-supported Syrian Democratic Forces, or SDF, was holding 800 foreign fighters from more than 50 countries. The numbers have increased by hundreds in the past two weeks, American defence officials said, as SDF members reclaimed territory from Islamic State and taken suspected fighters into custody. The war is in its final days, officials say.
In addition, defence officials revealed another group of at least 1,000 suspected Syrian and Iraqi extremist fighters who are in detention in Syria, a figure they didn't previously disclose. The actual number of those fighters could be even higher, officials acknowledged.
"I would characterize the number of ISIS fighters currently in SDF custody as thousands," Navy Commander Sean Robertson, a Pentagon spokesman, said in a statement, referring to Islamic State.
President Trump in December said he wanted to remove all of the more than 2,000 US troops from Syria. Last month, he shifted course under pressure from US allies and US military and diplomatic officials and agreed to keep hundreds of American troops in place.
The numbers of Islamic State fighters detained by the SDF are likely to continue to shift in coming days as the US-backed forces continue to reclaim land from Islamic State, officials said.
Over the weekend, more than 3,000 people, including 500 suspected fighters and civilians, surrendered to SDF around the eastern city of Baghouz, according to a Twitter message Monday by an SDF spokesman. In Baghouz, SDF and Islamic State are fighting over the last remnants of territory under the extremists' control.
The SDF said this week it had released 283 suspected Islamic State members as a "gesture of cooperation, fraternity and clemency," saying those released had "no blood on their hands."
The Kurdish and Arab fighters of the SDF, which the US considers to be the most effective fighting partner against Islamic State in northern Syria, had agreed to detain the terrorists as they captured them over the last few years, holding them in various camps in northern Syria.
As the US prepares to declare the end of the Islamic State caliphate, the physical terrain that up until now was controlled by the group, Washington has urged allies to take back foreign fighters from their respective countries. Although scores of detainees have been returned to their home countries, US officials acknowledge the process has gone slowly.
"These fighters are a global problem that requires global cooperation to solve," Cmdr. Robertson said. "We recognize the strain this puts on the SDF and appreciates their willingness to assist with this important task."
Most nations, however, have said they don't want to reclaim their nationals. Asking the SDF to continue holding suspected the prisoners could require the U.S. and its partners to give the SDF financial support as well as ensure that the detention centres don't violate international standards. It also isn't clear who would get custody of suspected Islamic State fighters who are Syrian.
"It creates a massive bottleneck for the SDF, which does not have the resources dedicated to house them, process them and to find a means by which to repatriate them to their home countries," said Nicholas Heras, a fellow with the Center for a New American Security's Middle East Security Program. "The countries of origin have different reasons for wanting to keep those fighters in Syria, but they can't be kept there indefinitely."
Iraq has taken back 200 fighters and said it could take 300 more, officials said. Last month, Iraqi Prime Minister Adel Abdul-Mahdi said Iraq would put foreign fighters suspected of launching attacks on Iraq on trial.
But Iraqi nationals who are suspected Islamic State supporters or members often can use family and tribal connections that extend across the Syrian-Iraqi border. They can "make their way back to Iraq without anyone having any idea where they are, what role they played in the ISIS organization or their ability in the future to advance the goals of ISIS incognito within the Iraqi population," Mr Heras said.
The figures of those imprisoned as fighters by the SDF don't include family members who were affiliated with Islamic State. Thousands of relatives now are being held in camps. The US and United Kingdom each have said they deny requests from women who have married Islamic State fighters to return home. The US has declared that one such woman, Hoda Muthana doesn't hold US citizenship; her father has filed a lawsuit intended to force the government to recognize her US citizenship.