The United States and Saudi Arabia pushed countries to return captured Islamic State fighters, with the kingdom’s top ambassador calling it “absolutely unacceptable” that wealthier countries avoided that responsibility.

“I would say to those countries, you must step up,” Saudi Foreign Minister Prince Faisal bin Farhan told a coalition conference in Riyadh.

Speaking at the same conference, U.S. Secretary of State Antony Blinken said repatriation was key to ensuring the lasting defeat of Islamic State.

He said detention centers were holding nearly 10,000 Islamic State fighters, 2,000 of whom are from countries other than Syria and Iraq.

“Failure to repatriate foreign terrorist fighters risks the possibility that they could again take up arms and attempt to restore ISIS’s so-called caliphate,” Blinken said.

Blinken announced nearly $150 million for Syrians and Iraqis to help improve humanitarian conditions, noting that hardship and disillusionment provided a breeding ground for Islamic State recruits.

Originally an offshoot of al Qaeda, the Sunni hardline group controlled one third of Iraq and Syria at its peak in 2014. Though it was beaten back in both countries, Islamic State militants continue to wage attacks.

Repatriations hit a record high in 2022, but more than 10,000 foreign women and children remain in the Al-Hol and Roj camps, according to Kurdish authorities.