There have been plenty of instances reported of drones flying contraband into jails around the world.
On the battlefield, Isis (Islamic State) has dropped bombs and grenades via drone. A possible drone attack is now a scenario considered for the security of any major outdoor international event.
German news site DW.com reported last year that "the research and development departments of the world's defence companies have barely begun to explore all the different uses" for drones. It says about 90 countries have drones in their military arsenals, including 11 with armed drones.
The Venezuelan Government says a drone attack targeted President Nicolas Maduro on Sunday. The President was unhurt but several soldiers were reportedly wounded. Despite scepticism that the attack could have been staged, video has surfaced showing a drone exploding and witnesses have said they saw it.
In hindsight, an attack on a senior political target via a drone was inevitable.
Writing in the Washington Post, former director of counterterrorism for the CIA Bernard Hudson says militarised drones "can carry several kilograms of explosives at speeds up to 160km/h with a range of 640km".
He bluntly states weaponised drones have a key advantage: "Most can fly lower than current technology is capable of readily detecting".
He says commercial aircraft are at risk, particularly at take-off and landing. Airport security focuses on ways to stop "threats from people who have access to the facility ... Airports are not designed to guard against purposeful attacks from the sky".
Wired last year looked at the problems of counter-drone measures - shooting them down could cause major damage - and possible solutions such as preventive drone swarms, catch devices or mini missiles.
As Hudson says: "A new and dangerous era in non-state-sponsored terrorism clearly has begun, and no one is adequately prepared to counter it."
