[Paradox]

Can you imagine if this thing had impacted a major US city? We would have ALL thought that we had been nuked by a terrorist, or Saddam. In our retaliation, all hell might have broken loose.... it would make for a cool book, or maybe a cheesy movie..

[weikel]

No an asteroid hit would have had a diffrent effect then a nuke all the dust etc it would have thrown into the air.

[Justa]

Space Command (or WrTF they're calling NORAD now) would pick it up on radar before impact. Probably not enough time to stop it but at least they'd know what caused the impact blast.