They (launcher of nuke) can use satellites to track their own missile and the interceptor.
Also separately, communication/radar works fine through reentry plasma once you go up to 20-50 GHz frequency.
Also separately, communication/radar works fine through reentry plasma once you go up to 20-50 GHz frequency.
If the interceptor misses the nuke's location by 50 microseconds it'll explode harmlessly a foot behind it. (The ICBM is probably traveling faster than the shockwave front of the explosive, depending on where it is)
I don't think a radar from satellite could be that precise, that fast, and get a signal out.