TORNILLO, Tex. — Late last week a sprawling tent city opened in Tornillo, outside El Paso. It is surrounded by chain-link fencing topped with barbed wire and hemmed in between the Rio Grande and I-10. Like several others along the United States-Mexico border, the Tornillo facility is intended to hold children apprehended for entering this country illegally.

But it’s also different. The other facilities, like the converted Walmart in Brownsville, are the equivalent of short-term holding cells where parents and children are separated and then processed out to other facilities. In contrast, the Tornillo facility, already home to perhaps dozens of teenage boys — very little is known about it, and no reporters have been allowed inside — will hold hundreds of minors, possibly for months at a time. Whatever the federal government chooses to call it, this is an internment camp. (On Wednesday President Trump said he was preparing an executive order “keeping families together.”)

Much of West Texas has been turned into a new front in the Trump administration’s war on undocumented immigrants. And wars take prisoners. Some 900 adult immigrants are locked up in the El Paso County jail. Children are held at facilities run by a private outfit, Southwest Key Programs. The government is reportedly planning to incarcerate still more people on military bases in El Paso, Abilene and San Angelo.

Like a lot of wars, too, this one is long on secrecy. When I approached the facility, I was brusquely told to leave. The local Customs and Border Protection spokesman claimed to know nothing about the camp, just steps out his station’s backdoor. The Health and Human Services Department returned no phone calls. Representative Beto O’Rourke, a Democrat from El Paso who led a march here Sunday, was told he would need to wait two weeks for an appointment; his colleague, Joe Kennedy III of Massachusetts, was simply turned away.