FBI director Christopher Wray warns of terrorists are planning to use drones in attacks, the threat is considered as imminent. Wray testified before the Senate Homeland Security and Government Affairs Committee. Counterterrorism agencies have established teams of intelligence experts who are working full-time to prevent such kind of attacks. Intelligence agencies worldwide fear possible terrorist attacks using drones for a long time. The unmanned vehicles could be equipped with chemical weapons or explosives, the alert is high, the official described the threat as ‘imminent'”]
Source: http://securityaffairs.co/wordpress/63551/terrorism/terrorist-drones-attacks.html