Saw the movie. Tried to read the book, but couldn't get past the first chapter... too technical for me.
They put the bomb in a vending machine.
In the book version, the target was the Super Bowl in Denver, curiously enough. They hid it in a white panel truck with an ABC logo and drove right in. When it goes off, the Russians are scratching their heads because apart from NORAD, which is designed to survive a nuke, they can't think of anything important in Denver, besides some govt. document centers and administrative stuff.
If this is really something nasty, it won't stay in Denver. They'll drive it to somewhere really symbolic and political.
Not surprised the movie version was completely changed. If Clancy had set out to write an anti-"West Wing", he could hardly have been more vicious. The Democrat President is more concerned with boinking his employees than paying attention to security briefings (at least he is a widower.) And the NSA has so little interest in Foreign Policy, and so many personal scores to settle, that she goes completely nuts in a crisis. And this was published in the MID-90's
F