[serf]

I thought that was cool until I read about the hibex at the bottom of that same page.

"However, it was literally a last ditch missile and was designed to intercept an incoming RV at less than 6,100m (20,000ft) altitude. At that altitude, the incoming RV would be traveling at around 3,000m/sec (10,000ft/sec) so a very fast reaction time was essential to insure interception. In fact, HiBEX was designed to have exited from its silo within 1/4 second and it accelerated at over 400g."

[twistedpair]

Note though that "interception" was a nuclear warhead (neutron bomb). It would still be all out nuclear war, but you'd rather set off a small nuke a few miles from the silos than have the incoming 25MT beast hit the base.