"We've also been talking with the Russians. There are large numbers of detainees and family members from Russia", the State Department official said. "The Russians have shown some interest in getting these people back, but that's still in an early stage".
The official noted the slow progress regarding the return of the foreign Daesh* fighters to foreign countries.
"We do this country by country. It requires a lot of background on the legal situation in the country, logistics of coordinating to get the people out", the official said. "We've had some success with the Middle Eastern countries. We've had some success with Central Asian countries. We've seen people being taken back to Europe only by, I believe, Bosnia, Kosovo, and one person taken back by Italy. Given that there are hundreds of people being held from Europe, Western Europe, and Central Europe, we are very troubled by this and it's a major issue of diplomatic discussion".
The official also pointed out that Washington is confident in the ability of the Syrian Democratic Forces (SDF) to secure the detention facilities.
The Syrian Democratic Council (SDC), the political arm of the Kurdish-led Syrian Democratic Forces, is "desperate" for funding to protect the prisons with captured foreign fighters who had joined terrorist groups, the co-chair of SDC Executive Council Ilham Ehmed said earlier in November.
Guarding captured terrorists became an issue in October when Turkey launched an offensive in northeastern Syria, where the SDF are operating.
Ehmed noted that as of now the SDF were guarding 6,000 fighters of Daesh and 12,000 Daesh family members.
On 9 October, Turkey launched Operation Peace Spring in northeastern Syria to clear the area of Kurdish militia it considers terrorists and Daesh. The United States and Turkey came to an agreement on 17 October for a 120-hour ceasefire in the area to allow the withdrawal of the Kurdish fighters.
As the five-day ceasefire came to an end, Turkish President Recep Tayyip Erdogan and Russian President Vladimir Putin reached a deal that would see the Kurdish fighters pull back from the border. In addition, Moscow and Ankara have begun joint patrols in the operation zone along the Turkish border.
*Daesh (also known as ISIS/ISIL/IS) is a terrorist group banned in Russia