Claiming them to be at 3500 feet which is possible but seems unlikely. The other unlikely indicator is that the disruption at Newark airport came shortly after the "drones" were spotted over another airport 15 miles away.
So, at least 15 miles range, 30 if they took off and landed at the same location, and they spotted the drones at 3500 feet -- not clear how they were spotted and more to the point, identified as drones.
Brian