The dysfunctional U.S. Congress is dithering about passing the so-called "shield law", designed to protect the American power system from electro-magnetic pulse (EMP) attack, despite the fact that the cost of the program would be about what the U.S. gives Pakistan every year, the political profit from which is becoming less clear all the time. It is often said that neither North Korea nor Iran would attempt to attack the U.S. by nuclear-tipped missiles, since such an attack would bring immediate and totally devastating retaliation. Therefore, the argument goes, don't worry about these countries having nuclear weapons, they are an empty threat.
Wrong. In the first place, a country with nuclear weapon capability can eventually miniaturize nuclear weapons and give them to terrorist organizations, which can introduce them with relative ease into almost any country. Secondly, once such a rogue regime has the delivery capacity, it can explode a nuclear device over a continental-sized country such as the United States, and create the electro-magnetic effect, which will render the entire electrical grid of the country inoperable, thereby bringing modern civilization to an end. By the time it was determined which country launched the attack, even if retaliation were possible from sites outside the country, there would be no society to protect and no government to order the counter-attack.