The recent report to Congress on the effects of an EMP attack is pretty darn scary.
EMP stands for “electromagnetic pulse.” It’s a side-effect of any nuclear or thermonuclear explosion. Basically it is a very brief but colossally intense burst of high energy (think X-rays) carried as a spherical shell that proceeds outwards at the speed of light from the blast point. It can easily — with quite a moderate-yield weapon — be strong enough to utterly destroy any electronic circuitry in line of site of the blast, at a distance of a thousand miles or more. If you saw the nuclear-scare TV movie The Day After 20 years ago, you’ll remember that the EMP stopped all the late-model cars in the midwest (by blowing the electronic fuel injection).
Well, a nuclear blast in space 300 miles above the US would EMP the entire country. Not just electronics, but electrical power equipment would go down. No power, no cell phones or computers… we’d be back to 1880. (Not the least creepy thing is that nobody would see this blast, unless they happened to be looking in precisely the right direction. You don’t get fireballs in space.)
Nasty. The only upside is, that with our stock of submarine-launched ballistic missiles, we could do this back to anyone who did it to us, and in spades. Yet even that upside has a downside: we might not be able to figure out who done it. Perhaps we should just quietly let it be known that if this happens to us, we’ll EMP all of the usual suspects.