Three military bases in Texas and one in Arkansas are being considered to house migrant children whose parents cross the border illegally, a sign that the Trump administration is moving forward with plans to separate families in the border crackdown.

The Washington Post and the Hill reported Defense Department notifications to Pentagon staffers said the Department of Health and Human Services will make site visits to the bases over the next for week to evaluate whether they can shelter children.

It's not clear whether the troops could be assigned to the bases where children will be sheltered. The Texas bases are the Army's Fort Bliss in El Paso, Goodfellow Air Force Base in San Angelo and Dyess Air Force Base in Abilene. Little Rock Air Force Base in Arkansas also will be evaluated, according to the Pentagon communications and HHS.

The bases would be used to hold minors under age 18 who arrive at the border without an adult relative or after the government has separated them from their parents. HHS is the government agency responsible for providing minors with foster care until another adult relative can assume custody.

The email characterized the site visits as a preliminary assessment. "No decisions have been made at this time," it states.

An HHS official told the post that the agency currently could house 10,571 children in its network of 100 foster-care facilities. But those facilities are at 91 percent capacity, the HHS official said, and the Trump administration's crackdown plans could push thousands more children into government care. The official said DHS has not provided projections for how many additional children to expect.

Trump officials say they are moving forcefully to halt a sharp increase in the number of families crossing the border illegally this spring, many of whom are Central Americans seeking asylum. U.S. border agents arrested more than 100,000 illegal border-crossers in March and April, the highest monthly totals since Trump took office.

Trump has seethed at the increase, singling out Homeland Security Secretary Kirstjen Nielsen for blame. He has ordered her to "close" the border and cut off the migration flows, which typically increase in spring with seasonal demand for rural labor.

Nielsen and Attorney General Jeff Sessions say the government will take the extraordinary measure of filing criminal charges against anyone who crosses the border illegally, including parents traveling with their children. In most cases, that means adults will be held at immigration jails awaiting court dates while their children are sent to foster care.

"If you're smuggling a child, then we're going to prosecute you, and that child will be separated from you, probably, as required by law," Sessions said in a speech last week.

"If you don't want your child separated, then don't bring them across the border illegally" he added. "It's not our fault that somebody does that."

By law, a person's first illegal border crossing is a misdemeanor, so federal authorities previously freed first-time crossers on their own recognizance -- a process that President Trump has criticized as "catch and release."

The extra prosecutions will mean parents will get separated from their children, potentially increasing the number of children put in the care of HHS.

Children held in HHS custody spend an average of 45 days in the government's care, the HHS official said, and they are provided with educational and recreational opportunities. The agency conducts background checks on potential sponsors for the minors, and in 85 percent of cases the children are released to a parent or other adult relative already present in the United States, the official said.

The use of military bases to house migrant children is not without precedent. At the peak of the 2014 child migration crisis, the Obama administration used bases in Oklahoma, Texas and California to shelter more than 7,000 children over a period of several months.

Critics of the family separation practices denounce the practice as heartless and cruel, saying it inflicts additional trauma on families fleeing for their lives from Central America's bloody gang wars.