Black UFO Recorded Flying Over Prohibited Airspace Manhattan, New York

On July 18, 2018 an unknown black object appears from behind a tower flying straight towards the camera of the person who has filmed the object.

The videographer: “Can someone explain what I just recorded? It's that a UFO?”

Manhattan is prohibited airspace. Within 2,000 feet horizontal in a built-up area, you will not be able to fly in that area. No aircraft may operate over Manhattan without valid Air Defence Clearance. 

With the 9/11 attack still in mind, how is it possible that this very low flying black object, UFO or perhaps a drone can fly in prohibited airspace without detection and intervention by Air Defence.