He did not name the two bases, but said the details wee being worked out, including how much capacity is needed.

The Pentagon had initially talked about four potential bases, but Mattis indicated the number is now two.

The Pentagon last week said it would make space available on military bases for as many as 20,000 unaccompanied migrant children detained after illegally crossing the US-Mexico border.

It wasn't clear Sunday if the housing would be limited strictly to children

Speaking to reporters traveling with him to Asia on Sunday, Mattis said the military has housed people in the past, including Vietnamese fleeing their country as well as Americans needing shelter in the wake of natural disasters.

The request for temporary shelter - amid a growing political battle over detained migrants - was made by the Department of Health and Human Services and accepted by the Defense Department.

Australian Associated Press