Thousands of ISIL detainees and their family members remain in camps and prisons in Syria.

Members of a coalition fighting the Islamic State of Iraq and the Levant (ISIL or ISIS) had a “difference of opinion” at a meeting in Washington, DC, on Thursday on whether detainees should be repatriated, the US Special Representative for Syria Jim Jeffrey said.

“There was some difference of opinion on whether they should be repatriated or whether that should be something that countries are still going to look at and think about in more detail, but nonetheless, that is acknowledged as a significant problem,” Jeffrey told a news conference.

Jeffrey’s statement came after Secretary of State Mike Pompeo urged members of the coalition to take detained fighters back to their countries and step up their funding to help restore infrastructure in Iraq and Syria, parts of which were severely damaged by conflict.

“Coalition members must take back the thousands of foreign terrorist fighters in custody, and impose accountability for the atrocities they have perpetrated,” Pompeo said at the opening of the meeting.

The armed group has lost most of its territory in Iraq and Syria. Former leader Abu Bakr al-Baghdadi was killed in a US raid last month, but experts and allies worry that the armed group remains a security threat in Syria and beyond.

Some 10,000 ISIL detainees and tens of thousands of family members remain the region. Washington is pushing European countries to take their citizens back, but so far they have been reluctant to do so.

Pompeo also asked coalition members to help fill the gap in funding to restore essential services and rebuild critical infrastructure in Iraq to facilitate the return of millions of displaced Iraqis.

“We will need help likewise in northeast Syria,” he said.

‘Fight not over’

Since his announcement last December that he would pull all US troops out of Syria, President Donald Trump has softened plans after a backlash from Congress, who say he enabled a long-threatened Turkish operation on October 9 against Kurdish forces in Syria. The Kurds have been one of the US’s top allies in the battle against ISIL.

Since then, Trump has agreed to keep a residual force in the northeast part of the country, focusing on preventing ISIL from staging a comeback and attacking the oilfields there. Washington is also keeping control of the airspace.

Speaking at the opening of the same event on Thursday, NATO Secretary-General Jen Stoltenberg also touched on the threat ISIL still poses. “The fight is not over. ISIS is still a threat. The situation in northeastern Syria remains fragile and difficult,” he said.

Pompeo also said there were growing concerns about the threat of ISIL outside of Iraq and Syria, and in places like West Africa and the Sahel. He said the US was planning to hold a specific coalition meeting to focus on boosting support for those areas.