No word yet on how many or for how long, but WaPo cites a source who says the operation will continue until Congress ends “catch and release” for illegals detained in the U.S.

So in other words, it’ll continue forever.

There was some question yesterday as to what Trump has in mind. Was he talking National Guard or regular military, which would potentially create a problem under the Posse Comitatus Act? Is he contemplating a presence much larger than Dubya’s deployment of several thousand troops more than a decade ago? “We’re going to be guarding our border with the military,” he said yesterday during a White House photo op, and “we really haven’t done that before.” That suggested something novel to come. When reporters pressed Kirstjen Nielsen about it today, though, she said no, this’ll be in line with what Bush and Obama did. It’ll be “strong” but familiar. Via the IJR:

DHS will be working with border states on particular deployments, another wrinkle of the Posse Comitatus Act. So long as the National Guard is operating under state authority, the statute doesn’t apply. But just to be extra careful and stay away from legal jeopardy under the Act, the Guard will also not be involved in arresting illegals or any other traditional “law-enforcement” functions. “What we’ll probably end up seeing is some vehicles and aerial assets supporting the border patrol, which is normal,” said an Obama-era Pentagon official to Military Times. Intelligence gathering and “road development” are also on the menu, per WaPo’s source.

There is one novel move we might see, though. Here’s Nielsen being asked about the border wall:

Sec. Nielsen to @jonkarl on U.S. military funding wall construction: "It's a good question, I'm only going to sidestep it because I'm not at the Department of Defense, and I'm not a lawyer over there." pic.twitter.com/FuyT2G5Q8A

— Evan McMurry (@evanmcmurry) April 4, 2018

There’ll be no wall (yet?) along the entire border but maybe bits and pieces of a wall on military land at the border. Trump was hoping last week to soothe populist anger over the lack of wall funding in the omnibus spending bill by having the Pentagon pick up the tab as part of its $700 billion budget, but there are legal pitfalls there. Most of that money is specifically appropriated by statute for particular tasks; insofar as Mattis has authority to move money around, there’s just not enough to cover the $25 billion that a wall would cost. He’d have to declare an emergency to authorize the spending and Congress might punish him for that by slashing next year’s funding. Mattis is allegedly not a fan of the idea of using military money to build the wall to begin with, which may explain the new plan to build on military border areas only. It ain’t much but it’s something Trump can point to as progress.