Originally posted by Russian
News said few weeks ago that during tests S400 intercepted targets at 56KM high with speed of 2.8KM/sec. Although it didn't say which version of 400.
All I know is that it's a long-range version of S-300, solid-fuel, active-guidance, ABM-capable just as 300. It's a replacement for S-200, being cheaper in service, mobile and much more flexible. Not having to fuel spare missiles (up to 60 IIRC for S-200) or even assemble them from factory storage containers makes it much more effective.
Optimists make Airplanes, pessimists make Parachutes, cynics make SAMs.