Three military installations are being considered to temporarily shelter unaccompanied immigrant children who have been apprehended at the border, officials said.

Malmstrom Air Force Base, Montana, and Fort Sill, Oklahoma, may be the closest of the three to receiving the children. They have already received initial assessments from the Department of Health and Human Services, but there are steps remaining in the approval process, said Defense Department spokesman Army Maj. Chris Mitchell. Fort Benning, Georgia, is also being considered, and HHS officials were reportedly scheduled to tour vacant property at Fort Benning today to determine its suitability for potential future use to house the children.

The bases are being considered because shelters at the border are beyond capacity to hold the children, ages 17 and under, while HHS officials work to find sponsors for them, usually family members. HHS has asked for an emergency appropriation of nearly $3 billion to increase shelter capacity.

Military installations have been used this way before.

In 2014, nearly 2,000 unaccompanied immigrant children were housed at Fort Sill for about two months.

Information was not available about when the decisions will be made about whether to bring the children to any of these installations. There’s a process involved, and the bases are in various stages of that process. Fort Sill and Malmstrom AFB are further along in the consideration process, Mitchell said.

The three bases are part of a request from HHS to temporarily house up to 5,000 children in property that is not currently being used, Mitchell said. There may or may not be other bases under consideration in the future, he said.

Acting Secretary of Defense Patrick Shanahan approved the request from HHS, and the request extends through Sept. 30, Mitchell said. That means the temporary facilities could be opened and stay open through Sept. 30, he said.

The types of facilities that could house the children varies from base to base, Mitchell said. “The driver of those requirements is HHS,” he said.

When unaccompanied children age 17 and under are apprehended at the border, and have no lawful immigration status, they are transferred to the care of the Office of Refugee Resettlement in the HHS Administration for Families and Children. That office is required to provide for their care until they are released to appropriate sponsors, usually a parent or relative, while their immigration cases proceed, according to a spokesperson for HHS.

Because of the large influx of immigrants who have no legal status in the U.S., the Office of Refugee Resettlement “is facing a dramatic spike in referrals’” of unaccompanied children, the HHS spokesman said, in an email response to questions. From October through April 30, ORR had received referrals of about 40,900 unaccompanied children. If that rate continues, it will amount to an increase of about 57 percent over fiscal 2018. Based on the anticipated increase, “ORR is preparing for the need for high bed capacity to continue,” according to the spokesperson.

“This effort will have no impact on DoD’s ability to conduct its primary missions nor on military readiness,” according to the HHS response.

Asked about the costs for the children’s housing, medical care, food and other needs, Mitchell said he didn’t have specific details, but added, “The effort that DoD puts into this is fully reimbursable from HHS.”