The US-backed Syrian Democratic Forces (SDF) are currently holding nearly 600 foreign fighters in custody, the Pentagon told reporters yesterday.
"As of July 2018 there are nearly 600 Foreign Terrorist Fighters from more than 40 countries in SDF custody," Pentagon spokesman Navy Commander Sean Robertson said, adding that the US military was also aware of more than 400 Syrian nationals who were also being detained by the SDF.
A US military official with the coalition told CNN that of the foreign fighters in detention, some 40 are from Russia, with around a dozen from Germany and France respectively.
The fate of foreign fighters has been subject to heightened debate since the establishment of Daesh in Syria and Iraq. US Defence Secretary Jim Mattis previously emphasised that the fighters' countries of origins needed to take responsibility for them.
The US has also recently expressed concern that the SDF will not be able to detain the fighters, highlighting the need for a more permanent solution.
"As you can imagine, it is a drain on their resources. They are not a policing organisation," US Army Colonel Thomas Veale, a spokesman for the coalition, said last month.
The SDF has secured swathes of land in the north of Syria, causing heightened tensions with neighbouring Turkey. Primarily made up of the People's Protection Units (YPG), an offshoot of the designated terror organisation the Kurdistan Workers' Party (PKK), Washington has backed the Kurdish militias in the fight against Daesh.
In May, Defence Secretary Mattis said that the US will not withdraw its forces from Syria unless peace is fully achieved throughout the country. "We do not want to simply pull out before the diplomats have won the peace, so you win the fight and then you win the peace," Mattis told reporters at the Pentagon.
The announcement came after conflicting statements from US President Donald Trump and the State Department earlier this year on the US' future presence in the region.
Earlier this month, two US senators visited Washington-backed forces in the northern Syrian province of Manbij and also emphasised the importance of American troops remaining in the region. "I will tell President [Donald] Trump it's important that we stay here to help you. You're friends of the United States and if we leave, it will be terrible," Lindsey Graham from South Carolina told militia leaders.
The US also confirmed this week that they it is aware of ongoing cooperation between the SDF and the Syrian regime of President Bashar Al-Assad, despite the US opposing the Syrian regime on the international stage.
"We are not encouraging the Syrian Democratic Forces to engage with the [Assad] regime," US Central Command Chief General Joseph Votel told reporters yesterday, but then acknowledged that interactions were a "fact of life."
In a statement, the head of the Syrian Democratic Council Riad Darrar stated that the SDF received only limited assistance in regards to specific services from the Syrian regime, but denied that they had reached any political agreement with the government.
However, Elham Ahmed, another official of the Syria's Democratic Council, confirmed earlier this week that the organisation intends to open offices in the Syrian regime-held areas in Damascus, Lattakia, Homs and Hama in an attempt to facilitate a "democratic solution to the Syrian file".