> A 20MT weapon detonation could result in disabling the global electrical production and distribution system, as well as permanently disabling the electronics

> A 20MT weapon detonation could result in disabling the global electrical production and distribution system, as well as permanently disabling the electronics necessary to move food, water, and medical supplies. The Tsar Bomba was a 50MT detonation and no such thing happened. There certainly are more electronics around today, but the EMP from a 20MT blasts, or even many 20MT blasts, would not be global, and even many electronics in range would be fine.