The defence of the C400 Vs missiles is not based on trying to shoot them down, it’s based on making the missile hit the wrong target. There are three layers of defence (none of them involves destroying a missile):
- In order to hit the target reliably an infrared visual recognition missile like the Taurus should first reach the general vicinity of the target to be able to actually spot it in infrared light (unless there is an assisting spotter to guide the missile). The Taurus, launched from 500km (for example) going at 1000 km/h will need around 30 minutes to reach the area of the target. The S400 is ready to fire 40 seconds after it powers up its radar. So, we can assume the AA missile from S400 and the Taurus were launched simultaneously. After firing a missile the S400 powers down and starts moving out of the launch area. It can move at 25km/h on a field and at 60km/h on a road. So, if there’s no road in the vicinity by the time the missile reaches the launch area the complex will be 10 or more kilometers away. If this works or not depends largely on what’s happening on the rest of the theater. Is there a ground spotter nearby to correct the missile? Is there an AWACS airplane in range to help the missile find the target? Is there an unjammed sattelite overhead to visually track the fleeing AA complex? Are there friendly (for the S400) jammers in the vicinity to isolate the incoming missile from outside communication? is there a nice forest nearby the S400 can drive into to hide from satellites and infrared guidance? etc.
- If plain old running away doesnt work, there is a last line of defence — “KB Radar” anti-missile system, which I mentioned earlier, tries to trick the missile into hitting the wrong target — it turns the real station off and powers on a decoy station, which imitates the infrared and radar signature of an operational AA complex (it also visually looks the same by the way). There is also an option of leaving that decoy complex in place (it’s an inflatable copy of the real thing, looks hillarious :)) in the launch area when the real one drives off. So the missile then successfully hits the “target” and the complex may even be reported as destroyed, but will in fact continue to operate.
- If the decoy doesnt work too (that could most likely happen if it was not powered up in time for some reason) there’s good old surviving the hit. The KEPD for example carries 100kg of explosives and I dont know of any cases of S400 being hit by KEPD, but I know a case of an S200 being hit by an AMRAAM missile — the radar vehicle was hit, as a result of the hit the vehicle lost a large percentage of radar surface, but surprisingly stayed operational. The complex as a whole can also remain operational depending of which vehicle was hit. Every complex consists of: Combat Control Vehicle (critical for operation), Radar vehicle (operates the main radar), up to 6 AA complexes, each consisting of 1 radar vehicle (with smaller radars with range up to 400km) and up to 12 launch units (usually mounted on 3 vehicles). There may additionally be present mobile radar towers for stealth targets detection. So, at the very minimum there are 6 vehicles (control, main radar, auxiliary radar, 3 launchers), at maximum there are 26 vehicles (control, main radar, 6 auxiliary radars, 18 launchers). The loss of any one vehicle is not critical for the operation of the complex. Of course, losing the command vehicle is bad, but it’s the most difficult one to hit as it performs no active operations, just stands there on the sidelines, losing the main radar is bad too, but the auxiliary radars can back-up in an emergency. Losing auxiliary radars and launch vehicles hurts long-term capabilities and is costly, but basically does not immediately disable the complex.