The US Central Command says Gen Michael Kurilla travelled to Syria where he visited Al Hol and Al Roj displacement camps that house tens of thousands of people with suspected links to ISIS.
Centcom said the visits this week were to "observe first-hand the current humanitarian conditions ... rehabilitation and reintegration efforts to return residents to their countries of origin”.
Al Hol holds about 51,000 people, the vast majority of them women and children, including the wives, widows and other family members of ISIS extremists.
Most are Syrians and Iraqis but there are also about 8,000 women and children from 60 other nations who live in a part of the camp known as the Annex.
They are generally viewed as the strongest supporters of ISIS among the camp's residents.
"Our continuing multinational effort to repatriate the residents of the camps to their countries of origin not only enhances security and stability in the region but, more importantly, eases this humanitarian challenge," Gen Kurilla said.
"The United States, SDF [Syrian Democratic Forces] and the global coalition remain focused and committed on the enduring defeat of ISIS while addressing the humanitarian and security challenges at camps in north-east Syria.”
Gen Kurilla also met Kurdish SDF members and discussed the continuing campaign to defeat ISIS.
At Al Hol and Al Roj, both in the north-east of Syria, UN experts have highlighted “dire” conditions and “significant humanitarian hardship”. About two thirds of the camps' population are children.
The Kurdish-led administration in north-east Syria in June said it would begin the trials of thousands of suspected ISIS foreign members who have been languishing in prisons and camps for years.
The US-backed and Kurdish-led SDF is holding more than 10,000 captured ISIS fighters in about two dozen detention units, including 2,000 foreigners whose home countries have refused to repatriate them.
Authorities in north-eastern Syria have called on the US-led coalition to make clear where it stands on Turkish drone strikes that have killed and wounded dozens of Syrian-Kurdish fighters in the past several months.
The main Syrian-Kurdish armed group is allied with Turkey’s outlawed Kurdistan Workers’ Party (PKK), which has led an insurgency against Turkey since 1984 that has killed tens of thousands of people.
Turkey has declared the PKK a terrorist group.
Agencies contributed to this report
