Complex sentence: It uses a millimeter-wavelength doppler radar to detect incoming warheads, then fires a defensive projectile, timed to detonate immediately above the target and spray it with a stream of splinters thereby defeating the threat.
Split into simpler sentences: It uses a millimeter-wavelength doppler radar to detect incoming warheads. It then fires a defensive projectile which is timed to detonate immediately above the target and spray it with a submunitions--thereby defeating the threat.