The Trump administration is preparing to separate migrant children from their parents and hold them at several military bases near the United States-Mexico border, according to Department of Defense notices sent to Pentagon staff.

According to The Hill, Department of Health and Human Services (HHS) officials will visit four military installations—three in Texas and one in Arkansas—to assess them for housing minors under 18 years of age who arrive at the border unaccompanied by adults or are separated from their parents.

Earlier this month, the Trump administration announced plans to prosecute parents who cross the U.S.-Mexico border. It’s an effort to deter immigrants, mostly Central Americans fleeing gang warfare, from arriving in the U.S.

In a speech at the San Diego-Mexico border, Attorney General Jeff Sessions announced a “zero tolerance” approach to border crossings.

“If you cross this border unlawfully, then we will prosecute you. It’s that simple,” he said. “If you smuggle illegal aliens across our border, then we will prosecute you. If you are smuggling a child, then we will prosecute you and that child will be separated from you as required by law.”

HHS provides care for unaccompanied minors, and the agency already holds some 700 immigrant children, who spend an average of 45 days in custody. In March, the American Civil Liberties Union (ACLU) filed a lawsuit challenging the Trump administration’s practice of separating families seeking asylum. The suit was filed on behalf of a mother from the Democratic Republic of Congo and her 7-year-old daughter, who were separated upon arrival in the U.S. and detained 2,000 miles apart.

“Whether or not the Trump administration wants to call this a ‘policy,’ it certainly is engaged in a widespread practice of tearing children away from their parents,” Lee Gelernt, deputy director of the ACLU Immigrants’ Rights Project, said in a statement upon filing the suit.  

On Wednesday (May 16), immigration advocates equated the notion of holding immigrant children at military bases with the practices of authoritarian regimes.

“What are we becoming? Totalitarian regimes take children away from parents to punish dissidents,” Frank Sharry, executive director of immigration advocacy group America’s Voice, tweeted. “America is taking children away from parents to punish refugees.”

Housing immigrant children on military bases is not unprecedented. During an immigration surge in 2014, former President Barack Obama greenlighted the use of military bases in Oklahoma, California and Texas to hold unaccompanied minors fleeing Central America.