Zap

PTD of the Whos. Small satellites equipped with high accuracy ion beams stationed on the orbit around the planet, capable of neutralizing incoming WMD on it's final approach. When the Zap receive a signal from long range scanners, they'll try to destroy the WMD by direct fire. The effectivity is almost 100%, but because of the time left to neutralize the threat is only about three seconds, some weapons might get through.