FILE - Teen migrants walk in line inside the Tornillo detention camp in Tornillo, Texas, Dec. 13, 2018. Thousands more migrant children may have been split from their families than the Trump administration previously reported.
FILE - Teen migrants walk in line inside the Tornillo detention camp in Tornillo, Texas, Dec. 13, 2018. Thousands more migrant children may have been split from their families than the Trump administration previously reported.

Acting U.S. Defense Secretary Patrick Shanahan has approved a request to identify places to potentially house up to 5,000 unaccompanied migrant children, the Pentagon said Wednesday.

In March, the Department of Health and Human Services (HHS) requested Pentagon support to identify locations to house unaccompanied migrant children through Sept. 30.

Migrant arrivals on the U.S. border with Mexico have been building steadily for months, driven by growing numbers of children and families, especially from Central America.

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FILE - Acting Secretary of Defense Patrick Shanahan gestures while speaking to members of the media aboard a military plane prior to his arrival at Andrews Air Force Base, Maryland, Feb. 23, 2019.

Pentagon spokesman Lieutenant Colonel Jamie Davis told Reuters that Shanahan approved that request Tuesday. Davis said HHS had made no request to actually house the children.

President Donald Trump on Tuesday said he was not reviving a policy of separating children from parents who had illegally crossed the U.S.-Mexico border, one day after media reports that his administration was considering putting it back in place.

In February, Trump declared a national emergency to help build a border wall, which would allow him to spend money on it that Congress had appropriated for other purposes. Congress declined to fulfill his request for $5.7 billion to help build the wall this year.

The Republican president's latest pronouncements, including a threat to impose auto tariffs on Mexico, are in response to the rising number of migrants.

Trump has previously turned to the military to help with his border crackdown.

Last year, the U.S. military was asked to house up to 20,000 immigrant children but the space was never used.

Last month, the Pentagon said it had shifted $1 billion to plan and build a 57-mile section of "pedestrian fencing," roads and lighting along the border with Mexico.

There are about 6,000 active duty and National Guard troops near the border.