The Pentagon will make space available on military bases for as many as 20,000 unaccompanied migrant children detained after illegally crossing the U.S.-Mexico border, a spokesman said Thursday.

Amidst growing protests from many quarters over detained migrants, the request for temporary shelter for the children was made by the Department of Health and Human Services (DHHS).

According to Lt. Col. Jamie Davis, the spokesman of the United States Defense Department, the acceptance of DHHS’s request would entail providing living spaces for the migrants at least through the end of this year.

Although it is not clear which bases will be used to house the children, DHHS had assessed facilities on four military bases, but the Pentagon said it had yet to be told which, if any, of the four will be used.

The four bases already assessed as potential shelter locations are Little Rock Air Force Base in Arkansas, plus three bases in Texas: Dyess Air Force Base, Goodfellow Air Force Base and Fort Bliss.

The US Defense Secretary, Jim Mattis had on Wednesday said he was not involved in decisions about housing migrant children detained after crossing the border.

The children, who would be housed on military bases are those who cross the border illegally by themselves, as opposed to those accompanied by adults.

On Wednesday, President Donald Trump signed an executive order to keep together children and parents apprehended for crossing the border illegally for at least 20 days.

The order also directs the Justice Department to seek legal ways to permanently remove the threat of separation.