There are a number of technologies that exist for shooting down ICBMs, and their effectiveness depends on a number of factors.
One technology is the use of long-range interceptor missiles, which are launched from a distance in order to intercept and destroy an ICBM before it reaches its target. Another technology is the use of ground-based interceptors, which are positioned near potential targets and are designed to intercept and destroy an ICBM shortly after it is launched.
The effectiveness of these technologies depends on a number of factors, including the accuracy of the interceptor missiles, the number of interceptor missiles available, and the ability of the interceptor system to differentiate between real ICBMs and decoys or false targets.