I’m actually impressed with the US and Israeli progress on drone defense. Laser defense is going to be the primary solution and the US and Israel are working diligently. Unfortunately even laser can be swarmed, attacks can be scheduled during fog (lasers don’t work through fog) etc. All systems have weaknesses and ultimately it comes down to an economic battle. Your enemy must not have the resources to use this asymmetric warfare. So, you increase the chance of reprisal attacks working (raising the price of attack from a $500 drone to the attackers life), increase the cost of a successful attack by being able to defend against a large number of drones at the most probable attack location.

The majority of the anti-aircraft defenses are targeted at standard warplanes. The S400 is one of those. Shooting an S400 missile at one of these tiny drones is like shooting a shotgun at a swarm of gnats. You’re not taking out the swarm and you just spent a ton of money to battle something insignificant. The power of these drones comes not from the individual, but the ability to coordinate together. In IT lingo, it would be like trying to battle a DDOS botnet. Further, the S400 is designed to detect a huge airplane. Yes those planes are radar absorbing and reflect radar away from the receivers, but they don’t really resemble a bird. They’re too fast, they go straight, they reflect radar strongly in other directions (to be detected by radar receivers distant from the transmitter) and at their size are capable of being detected by other techniques. These small drones could be made to look like birds from a radar perspective. Hard to justify shooting your S400 at a bird.

The justification for spending more money on defense is that the more you spend, they better you’re protected. I don’t believe that to be completely true, but our investments in laser defenses is justifiable.