Russian doctrine should be in a state of flux on the question of low-performance drones. Combat experience in Syria will take some time to percolate. S-400 doctrine on over-the-horizon threats seems to be is to cue remote systems (Pantsir) to deal with the threat, or track the targets with aerial surveillance, or use electronic warfare to jam them. AWACS or MIG-31's are too expensive to keep on patrol 24 hours. But, low performance drones seem to demand low-performance (ie, cheap) solutions. A little 24-hour aloft air control drone with a little radar good for some number of miles against a drone size target might be completely useless against a missile or jet, but perfect for dealing with cheap drones. In which case, the S-400 system is suited to become the air traffic controller.
Edited by glenn239, 04 November 2019 - 1253 PM.