ISIS's Drones Are Effective

With $20,000 or $30,000 in funding, a group of insurgents could have everything they would need to start putting together a small air force. ISIS's defeat in Mosul did not mean that all their knowledge and capability died out. The weapons made will only get more efficient and deadlier as different groups produce them, work out kinks and upload their designs to the Internet. Those files will spread, and they will wind up in the hands of domestic extremists, not just ISIS.