Magnetic Pulse (EMP) from the nuclear blast, he says. "Its  all theoretical. Its never happened before." In actuality, the  United States detonated a 1,450 kiloton warhead at an altitude of  248 miles, 9 July 1962, in the Dominic Starfish Prime nuclear test.  Due to its altitude, the explosion spread an EMP wave that caused  notable outages and damage in Oahu, Hawaii, 800 miles away.