Disk-shaped UFO over Monroe, USA

On July 22, 2015 at 23:45, an inhabitant of Monroe (State of New York, USA) has spotted during about 30 minutes a disk-shaped UFO. Object emitted smaller red lights and a larger greenish spot light. What is it?

Witness statement:

The object was in the distance, late at night, not so easy to make out as to exact shape. It basically hovered for a long time. It seemed to be getting closer for a few minutes, but then did not appear to have actually moved. We both thought it looked like a classic hat-and-brim shaped flying saucer, as depicted in films, with red lights at either edge and a greenish-blue larger light, almost like a spotlight directed towards the ground, in between the red lights. My husband thought he could make out a tower-like structure extending up over the object with a red light at the top. I attempted to shoot video with a small camera, but it was too dark; object just appears as a whitish blob. Can’t rule out a drone, but appears large from a distance.

Photo: Monroe town hall, on left next to village hall (Daniel Case / Wikimedia - CC BY-SA 3.0)