Pentagon agrees to provide space for 20,000 migrant children.

WASHINGTON — 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.

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, said the spokesman, Army Lt. Col. Jamie Davis.

A Pentagon memo to members of Congress, obtained by the Associated Press, said it has been asked to have the facilities available as early as July, through the end of the year. It said Health and Human Services personnel or contractors for the department “will provide all care for the children,” including supervision, meals, clothing, medical services and transportation.

It’s not clear which bases will be used to house the children. Health an Human Services has assessed facilities on four military bases, but the Pentagon said it has not been told which, if any, of the four will be used. The Pentagon said it will have no role in operating the temporary shelters, which would be controlled by the department.

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

Defense Secretary Jim Mattis said Wednesday he is not involved in decisions about housing migrant childre. But he said the Pentagon will provide whatever support is requested by either the Department of Homeland Security or Health and Human Services. The Pentagon memo to Congress said that as of Wednesday it had received no request from Homeland Security.

The children who would be housed on military bases are those who cross the border illegally by themselves.