>No way they do an risky exercise that endangers the public.
Speaking from professional experience?
10 second web search yields:
http://www.thedrive.com/the-war-zone/25458/commandos-ride-black-hawk-helo-and-stealth-boats-during-shadowy-exercise-in-miami-port
https://theaviationist.com/2018/09/12/watch-night-stalkers-mh-60-black-hawk-and-mh-6-little-bird-helicopters-fly-underneath-the-brooklyn-bridge-in-nyc/
http://www.thedrive.com/the-war-zone/20255/night-stalker-choppers-freak-out-manhattan-with-nighttime-low-level-training-exercise
https://www.twincities.com/2014/08/18/helicopter-training-over-cities-continues-through-thursday/