(CNN) The Trump administration is exploring holding children caught crossing the border on military bases, signaling the latest effort to move forward with plans to split up families who cross the border illegally.

According to a Defense Department official, staffers from the Department of Health and Human Services have begun informally looking at three sites in Texas and one in Little Rock, Arkansas. No official request has been submitted.

The official said Defense Department facilities had been used in this manner before, including during the Obama administration. If the facilities are to be used for such a purpose, HHS must assure the Pentagon there will be no impact on the military's readiness or training efforts and must reimburse the Defense Department, the official said.

The Washington Post previously reported the news. According to its report, an email sent to Pentagon staff characterized the site visits as a preliminary assessment, stating that "no decisions have been made at this time."

The Administration for Children and Families at HHS responded with a statement that said in part: "The Office of Refugee Resettlement at HHS' Administration for Children and Families is responsible and required to care for minors who are in the country illegally without a parent or guardian. Operating this program requires routinely evaluating the needs and capacity of an existing network of approximately 100 shelters in 14 states. Additional properties with existing infrastructure are routinely being identified and evaluated by federal agencies as potential locations for temporary sheltering."

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