You dont belive my words so i will give you what Gambit send me on mail about ABM .. he is an expert ,you cant argue about it ..I hope he dont mind me posting this here ..
Technically speaking, there is no difference between ICBM or lesser distance missile defense. Ballistic missiles of all distances have the same parabollic trajectory, only their altitude differs with intercontinental ballistic missiles (ICBM) have a suborbital component in their flights, meaning ICBM warheads momentarily became 'spacecrafts'. But all ballistic missiles have the same basic flight characteristics: vertical launch or 'boost' phase, an arc or 'mid-course' phase and a descent or 'terminal' phase.
Ballistic missile defense is about intercepting the warhead at all three points -- in theory. However, since it is improbable to know when a missile is launched, the defense is left with trying to intercept the warhead at the mid-phase and the descent points. A mid-phase interception require the interceptor to meet the warhead at the apex of its journey.
, the basics of interception are the same for lesser range missiles. So some people in the closed discussion are wrong about there is a difference between ICBM and shorter range defense. Anti-ballistic missile (ABM) defense means exactly that -- ballistic type of missiles. Cruise missiles do not have ballistic trajectories. Air combat missiles do not have ballistic trajectories. These two types exploit aerodynamics principles.
Intercontinental (ICBM) distances have the longest flight time, up to thirty minutes, but can be less than fifteen. Shorter range BM give the defense less response, making development on detection, response formulation and interception more difficult,
giving some people a false impression that ABM defense is mechanically different than ICBM defense. No difference. The 'IC' is really meaningless as far as the mechanics are concerned. It is the 'BM' that matters. Shorter range BMs are still 'ballistic' in trajectories. Take the above graphics and lower it down several thousands kms in altitude and you will see there are no differences.
So since it is near improbable at this time to intercept a BM at its boost phase, that leave the defense mid- and terminal- phases to work with. If there is a suborbital component to the BM's flight, creating an exo-atmospheric interceptor can be quite technically challenging. That leave the terminal, or descent, phase available for interception. At this point, the warhead is in atmospheric environment and this is why some people are wrong about ABM defense is different than ICBM defense. To intercept an ICBM or lesser range missile during its terminal phase differs only at the altitude factor. The ICBM warhead begin its descent, or terminal phase, from orbit. The shorter range BM warhead begins its descent when it is still endo-atmospheric.
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Dont always listen to what your Chinese papers say ..