A very real and credible threat to our national security. No, let me rephrase that, a very real and credible threat to our entire way of life. Hyperbole? Research it and judge for yourself! See the links below and/or simply Google Electromagnetic Pulse.
Electromagnetic Pulse destroys electronics. Detonate a device that disperses an EMP across a large enough section of the country and *poof* we are in serious trouble. The car won't start. The lights are off. The TV won't work. And (dare I say it) cell phones & computers are fried. You can see that this would make for a very bad day...
If a nation (Iran or North Korea for instance) can lauch a satellite into space, they can potentially launch an EMP strike against us: "A nuclear weapon with a burst height of approximately 100 kilometers could expose objects located within an area 725 miles in diameter to the [devastating] effects of EMP." [Heritage]
"...it would take only one to three weapons exploding above the continental United States to wipe out our entire grid and transportation network. It might take years to recover from, if ever." [Newsmax]
For all the really fun details check out the government's EMP threat assessment at the Internet Archive.
The relevant links:
Newsmax: Newt Gingrich: A Single Nuke Could Destroy America
Heritage Foundation: Electromagnetic Pulse (EMP) Attack: A Preventable Homeland Security Catastrophe
Internet Archive: The report of the Commission to Assess the Threat to the United States From Electromagnetic Pulse Attack
This is a threat that we should not ignore, particularly as rouge nations become more adept in developing their missile technologies. Maybe we aren't so afraid if they get hold of one or two little nukes, but then maybe we should be. I for one would rather not be thrown back into the 1800's. How many of us would last a week in that environment?
Can anyone say "missile defense?"