(Eric Gay/AP Photo)

The Department of Health and Human Services is in talks with the Pentagon to use additional bases to house thousands more unaccompanied minors from Central America that are swamping its facilities.

The Pentagon is housing 2,700 minors at unused housing facilities at three military bases; it has authorization to house up to 3,600 children at those facilities for 120 days.

WATCH: The Invisible Crisis: Small Children Crossing the US Border on Their Own

The Defense Department is allowing HHS to temporarily use vacant housing facilities at Lackland Air Force Base in San Antonio, Texas; Ventura Naval Facility in California and Fort Sill, Oklahoma.

Pentagon Press Secretary Rear Admiral John Kirby told reporters Tuesday that the Pentagon is processing more requests from HHS to house more children. "We're in discussions with them about trying to find additional space for additional children," said Kirby.

Kirby would not detail how many additional bases are under discussion but a Defense official says Fort Lewis, Washington and Fort Drum, New York are two options being discussed.

Border Patrol officials estimate that as many as 60,000 unaccompanied minors from Guatemala, Honduras and El Salvador may enter the United States illegally this year.

READ: DHS Chief Blames 'Horrible' Conditions for Child Immigrant Spike, Not Deferred Action

By law HHS must provide for the well-being and care of unaccompanied minors until family members or guardians are located who can take care of them while their immigration cases are determined. In May the Pentagon agreed to the use of a temporary housing at Lackland after HHS's own facilities began to overflow.

"We're proud to be able to support them in this regard, but it is a temporary mission," said Kirby. "And it's not something that we see an enduring arrangement, and I don't think HHS would say that they would think it's an enduring arrangement, either."

Kirby said Defense Secretary Chuck Hagel wants to help HHS as much as possible in helping care for the children. "He wouldn't have signed up to this if he wasn't," said Kirby. "He understands the importance of making sure that these children get the care that they need once they get inside the country."

The spokesman said the effort is not affecting military readiness as the Pentagon's merely providing facilities.

READ: More Than 50% of Unaccompanied Immigrant Minors Remain in US

"The facilities that we're using for the children are already vacant facilities that are not being used for any other purpose. And I can assure you and the American people that American military operations are not being curtailed or degraded in any way by us doing this very limited, temporary support mission to Health and Human Services," said Kirby

He added, "The responsibility for the children lies with Health and Human Services. We are providing the facilities, the physical infrastructure, the places for them to sleep and to bathe and to eat, but we are not responsible for the children themselves. It is an HHS mission."

Kirby anticipates future discussions with HHS to lengthen the agreement for the use of the three bases currently in use.

The HHS will reimburse the Pentagon for the costs of the use of its facilities to temporarily house unaccompanied minors.