When a nuclear weapon is detonated, it releases an electromagnetic pulse.  Electromagnetic pulse (EMP) is a series of magnetic waves that shuts down any electronic device in its path from toaster ovens to supercomputers.  There are means of manufacturing a device that creates EMP without the nuclear explosion.  Soon I plan to have detailed schematics and instructions for building your very own EMP generator.  It's a great way to piss people off and it's easy enough to make.