As more and more nations get high tech (and low tech) drone technology, the U.S. Army is fast tracking their counter-drone weapon systems, including lasers and missiles.
A drone attack could be extremely scary, especially to think that each drone in a swarm could have explosives on it. Drones can launch missiles, hit within a swarm, or utilize technology to recon enemy locations. These capabilities leave defenders in a vulnerable situation.
To defend against these things the Army is utilizing Electronic Warfare to jam them, missiles to knock them out of the sky, and other technologies Raytheon is working on to sense-track-hit drones. Our favorite at Macatawa Unmanned is the HEL, or High Energy Laser. The only problem is, missiles cost a lot of money and as the military found out in Iraq, it is not worth firing a Stinger missile at a $1000 off the shelf drone. They also found out that it is extremely difficult to identify drones utilizing the current detection equipment. A lot of this equipment can mix drones up with small birds, or cost millions of dollars with countless algorithms.
The answer lies somewhere with a layered system, a defense in depth utilizing different drone killing options that depend on the range and capabilities of the vehicles and the combat environment.