More: The account, which has not been previously reported, was shared by the F-15 pilot with intelligence officials during a debriefing after the incident. It immediately set off a firestorm of debate within the US intelligence community that has yet to be resolved.

If the airman really saw what he described " a formation moving in unison " it would be an alarming advance in Iranian drone capabilities.

"Multiple drones interconnected and moving as one with smaller drones below the bigger drones like legs," one of the sources familiar with the pilot's witness account told CNN. "Real alien sh*t."

Another source told CNN the pilot described witnessing a "minefield of drones" in the air.

If they can do this over their cities imagine what they can do with a swarm full of explosive packed drones.