Since the Long Hot Summer of 1967, or even the Rodney King riots in Los Angeles in 1992, the feds have showered local police departments with billions of dollars in armored carriers, grenade launchers and other war-zone gear. Some was military surplus; others, shiny new stuff paid for by Homeland Security grants in anticipation of foreign terror threats. Give a department new gear, and odds are it will find a way to use it. (Well, not always, as when police in Louisville were given bodycams but failed to turn them on during a shooting that left a black business owner dead.)

The various layers of armor, mechanization and remote operation that we see today alter the relationship between police and protesters from one of the police as neighbors who are defending communities to something that, fairly or not, begins to look like an impersonal army of occupation. That worsens social divisions. We all saw the videos of tension being defused by police engaging the crowd in conversation. It didn’t always work, but sometimes it did. Put the officer in an armored vehicle or helicopter, and that’s not as likely to happen.

The need for now is to stop the violence on all sides. When things settle down, we’ll want to study which style of policing worked better in calming unrest: the kind where warrior cops in sci-fi garb occupy terrain, or the kind where recognizable humans, the sort who can read each others’ expressions, face off in the public square.