The U.S. and its European allies clashed Thursday over what to do with thousands of former ISIL fighters jailed in Syria and Iraq, with Washington calling a French proposal to try fighters in Iraq "irresponsible."

Senior officials from more than 30 countries discussed the campaign against ISIL in a meeting in Washington proposed by France. Many detained foreign fighters are from Europe, but countries have been reluctant to take them back.

U.S. Secretary of State Mike Pompeo urged coalition members to take back and prosecute their nationals to help keep ISIL from regaining territory. "Coalition members must take back the thousands of foreign terrorist fighters in custody and impose accountability for the atrocities they have perpetrated," he said. 

The meeting came amid concerns about the U.S. commitment to the fight against ISIL remnants. Those concerns have increased as President Donald Trump has pressed to withdraw American troops from Syria.

But Nathan Sales, the U.S. State Department's counterterrorism coordinator, acknowledged that "there is, candidly, a difference of opinion about the best way to resolve this problem."

"The U.S. thinks that it's inappropriate to ask Iraq in particular to shoulder the additional burden of foreign fighters, particularly from Europe," Sales told reporters after the one-day meeting. 

Sales' comments clearly were directed at France, which has opened talks with Iraq about trying foreign nationals. European nations, such as France and Britain, have no desire to see the return of battle-hardened supporters of the ultra-violent group, which has claimed responsibility for a slew of grisly attacks against civilians. 

French Foreign Minister Jean-Yves Le Drian, in a statement ahead of the Washington meeting, said he would take up the essential question of maintaining the certain and lasting detention of the extremists. France wants to highlight that nothing is called into question and that crimes they have committed in Iraq and Syria do not remain unpunished, the foreign ministry said. 

During the meeting, Pompeo said it will also be critical to keep ISIL from expanding its reach to other areas, notably the Sahel region in Africa, where he said the group "is outpacing the ability of regional governments and international partners to address the threat." 

NATO Secretary-General Jens Stoltenberg, speaking alongside Pompeo, acknowledged that there were differences among alliance members on Syria, where the situation he said "remains fragile and difficult." 

"But at the same time, we agreed on the need to safeguard the gains that were made against our common enemy ISIL," he said.  

(With input from AP and AFP)