Trump told the crowd, "One rough hour, and I mean real rough, the word will get out, and it will end immediately. End immediately. You know, it'll end immediately."

Political scholars, historians, and experts on authoritarianism have been quick to call out this rhetoric as incredibly dangerous.

Trump told the crowd, "One rough hour, and I mean real rough, the word will get out, and it will end immediately. End immediately. You know, it'll end immediately."

Political scholars, historians and experts on authoritarianism have been quick to call out this rhetoric as incredibly dangerous.

Journalist Jim Stewartson warned that Trump's call for a "really violent day" of policing brought to mind Nazi German's Kristallnacht of November 9, 1938, when Adolf Hitler supporters attacked Jewish businesses all over Germany. Trump didn't use the German word "Kristallnacht" specifically, but Stewartson argued that Trump was promoting something comparable.

Stewartson tweeted, "In PA today, Donald Trump gave one of the most dangerous speeches of the 21st century by describing his strategy for reducing crime as Kristallnacht, 'one extraordinarily rough, one really rough nasty day. One rough hour. You know it'll end immediately…. I've seen this described as The Purge, which is wrong. That was a movie where the population was set against itself. This is the description of state-sponsored wide-spread violence. It actually happened."

Scholar Jamie Chapman, similarly, posted, "For those history buffs out there - yes, he's calling for the Night of Broken Glass (Kristallnacht)."

Historian Dr. Gina van Raphael wrote, "Kristallnacht. That's what Trump is asking for with this purge in a day of violence. I hope the younger ones understand what that means."