https://www.newscientist.com/article/2173039-the-us-has-an-anti-drone-gun-that-shoots-drones-at-other-drones/

Attacks using consumer drones are on the rise. In 2017, ISIS forces in Mosul attacked US-backed Iraqi troops with dozens of consumer drones dropping grenades, and earlier this year a swarm of small drones attacked a Russian airbase in Syria.

Such attacks are difficult to counter with existing weapons.  Their size makes them difficult targets, and the lack of heat and radar signature makes it …