Along with the superiority of our troops, though you should take into account that we face irrregular troops that can attack at any point of the LOC. More like the Lawrence/Beduoin campaigns vs. the Turkish railways. Again, our technical expertise keeps them from disappearing into the desert, but they can hide in any population center along the route. I'm surprised that we haven't seen more of this -- I think Saddam and his advisors are incompetent (luckily!).

I disagree with your assertion that we could not build up longer for fear of international opinion derailing our attack. I don't think anything could deter the attack, and I don't think the administration gave it much thought.