"In this case the proper authorities would be the equivalent of the department of state in the country", Col. Ryan Dillon said in an address meant for the press through a video call from Baghdad.
It is not the first time an American citizen fighting for IS has been detained. Last week, they broke an Islamic State siege of the provincial capital, Deir al-Zor city, which sits on the western bank of the river.
Coalition forces were not party to the deal and were opposed to it.
Syrian regime forces are fighting for Dayr Az Zawr southeast of Raqqa, while SDF continues its offensive north of that city.
Hezbollah acquired the remains of eight Lebanese soldiers and two Hezbollah terrorists and an Iranian military adviser.
The current location of the United States citizen has not been released.
The Wall Street Journal reported Wednesday that opposition activists said the convoy of buses was able to reach Deir Ezzour province, an ISIS-held area, after the coalition ended its aerial surveillance and airstrikes on the group.
"In general, I don't think we're better off bringing these people to federal court", where they are represented by "court-appointed lawyers" and given "discovery rights to find out our intelligence", Sessions said. "We are fighting terrorism in Iraq and we are killing them in Iraq". "Would he have insight on whether they're sending folks away from Iraq and Syria in a systematic way?"
"As SDF forces retake territory from ISIS", Manning said, "we have seen cities, towns and communities form civil and military councils and establish that basic governance".
While in eastern Syria, government forces also captured a new neighborhood from ISIS in the eastern city of Deir el-Zour.
A man believed to be an American citizen who was fighting with Islamic State terrorists has surrendered in Syria and is now in USA custody, raising questions about how the Trump administration will deal with such detainee cases.