NATIONAL GUARD IN D.C.: National Guard troops began deploying in Washington, D.C., yesterday, with some joining city police last night. The full contingent of 800 troops expected to be operational by the end of the week.

The city’s police and federal officials took the first steps Tuesday in an uneasy partnership to reduce crime in what President Donald Trump called — without substantiation — a lawless city.

If President Trump deploys troops to other American cities, experts say it would be a clear departure from founding principles and invite a legal challenge.