Pentagon spokesman Lt Col Michael Andrews told The New York Times the bases would house “unaccompanied alien children”, although the paper reported other federal agencies as giving conflicting information on the matter.
The move has added to the chaos on the US-Mexico border following US President Donald Trump’s reversal of a policy that separated more than 2,300 children from their parents over the past several weeks.
It was part of the Trump administration’s zero-tolerance immigration policy — a signature campaign promise of Mr Trump — but the reversal has created uncertainty for the migrants and the federal agencies in charge of prosecuting and detaining them.
A senior Trump administration official said that about 500 of the more than 2,300 children separated from their families at the border have been reunited since May.
It was unclear how many of the children were still being detained with their families.
Federal agencies were working to set up a centralised reunification process for the remaining separated children and their families at a detention centre in Texas, the anonymous official said.
‘Republicans should stop wasting their time on immigration’: Trump
As reports swirled, Mr Trump told his fellow Republicans in Congress to “stop wasting their time” on immigration legislation until after November, dismissing his party’s struggle to surmount internal divisions.
Stubborn differences between conservative and more moderate Republicans in the House have stalled immigration legislation on Capitol Hill, with a vote on a compromise measure delayed until next week.
Mr Trump said that even if a measure passed, it was doomed in the Senate.
Elect more Republicans in November and we will pass the finest, fairest and most comprehensive Immigration Bills anywhere in the world. Right now we have the dumbest and the worst. Dems are doing nothing but Obstructing. Remember their motto, RESIST! Ours is PRODUCE!
— Donald J. Trump (@realDonaldTrump) June 22, 2018
Both bills have received backing from Mr Trump but are opposed by Democrats and immigration advocacy groups.
The two bills would fund Mr Trump’s proposed wall along the country’s shared border with Mexico and also reduce legal migration.
A seven-year-old boy and his migrant mother separated a month ago were reunited on Friday after she sued in federal court, and the Justice Department agreed to release the child.
The two were reunited at about 2:30am (local time) at Baltimore-Washington International Airport in Maryland.
The mother, Beata Mariana de Jesus Mejia-Mejia, had filed for political asylum after crossing the border with her son, Darwin, following a trek from Guatemala.
She said she started crying when the two were reunited and said she was never going to be away from him again.
Other immigrants who remained locked up and separated from their families struggled to stay in touch with children who are in many cases hundreds of kilometres apart.