Acting defense secretary Patrick Shanahan has approved a request from the Department of Homeland Security to construct temporary tent housing facilities for 7,500 adult migrants to alleviate what the Pentagon described as an ongoing humanitarian and security crisis on the southern border.

Maj. Chris Mitchell, a spokesman for the Pentagon, said in a statement late Wednesday that the temporary facilities would house “single adult male and female aliens” processed by Customs and Border Protection and turned over to the custody of Immigration and Customs Enforcement.

The Pentagon will loan and erect tents on prepared land identified by DHS and conduct site assessments over the next two weeks to determine the scope, cost and timeline to construct the temporary housing facilities in Arizona and Texas, Mitchell said.

“Military personnel will not operate the facilities and will only erect the tents,” Mitchell said. “Operating the facilities remains the responsibility of DHS.”

Officials will be conducting the site assessments in the Tucson and Yuma sectors in Arizona and near the Tornillo, Donna, Laredo and Del Rio ports of entry in Texas, according to Mitchell.

DHS is asking the military to erect the temporary housing because the federal agency is facing limited capacity to house the large flow of migrants who are being apprehended by Border Patrol after coming over the southern border into the United States.

The flow of migrants over the southwestern border with Mexico has been spiking, straining an already stretched system for processing and housing those who are apprehended. The influx has led to what officials are describing as an emergency due to the overwhelming number of people in custody.

CBP detained 109,144 migrants in April, a 6% increase from the previous month and the largest number to cross the border in a month since 2007. Nearly 45,000 unaccompanied children have crossed into the United States in the past six months alone.