Trump wants to "put tents up all over the place" for migrants.

President Donald Trump said during a Monday morning interview with Fox News that the federal government will "build tent cities" for thousands of asylum-seeking migrants slowly making their way north toward the U.S. border in two large caravans from southern Mexico and Central America.

Mr. Trump said in the interview with Laura Ingraham that the administration will detain any Central Americans who complete the more than thousand-mile trek while they await "their trial" after claiming asylum. The group is still weeks or more away from reaching the U.S. border.

"We're going to build tent cities. We're going to put tents up all over the place. We're not going to build structures and spend all of this, you know, hundreds of millions of dollars — we're going to have tents," Mr. Trump said.

But tent cities are not a cheap solution. Hundreds of millions of dollars is how much the one tent city currently operated by the federal government is costing this quarter alone. The U.S. Department of Health and Human Services (HHS) said in a Sep. 18 announcement in the Federal Register that it expected to spend $367 million on the government's tent city at the Tornillo Port of Entry in Texas in just the final three months of the year.

That facility currently houses about 1,500 unaccompanied migrant minors, but was recently expanded to make room for up to 3,800 beds.