Electromagnetic Pulse (EMP) Weapons
"Foreign adversaries may aptly consider nuclear EMP attack a weapon that can gravely damage the U.S. by striking at its technological Achilles Heel, without having to confront the U.S. military," reads the report, which notes how foreign actors could use EMP attacks virtually anywhere in the world.
"Super-EMP" weapons, as they are termed by Russia, are nuclear weapons specially designed to generate an extraordinarily powerful E1 EMP field. Super-EMP warheads are designed to produce gamma rays, which generate the E1 EMP effect, not a big explosion, and typically have very low explosive yields, only 1-10 kilotons ... Even EMP hardened U.S. strategic forces and command, control, communications and intelligence (C3I) systems are potentially vulnerable to such a threat. -Firstempcommission.org
Comment: Since the only country that has dared use weapons of mass death offensively on such as scale is the US, one can assume the real threat in the above scenarios is the US, however there are natural events which produce EMPs and the US would be wise to look into protecting itself against those: