Saddam Hussein believed that he didn't have to win the war... all he had to do was keep up a steady bleeding of us (what is occurring now), and we would run away.
What prompted such a strategy. Why... Vietnam, Beirut, Somalia, etc.
In the 1990's, our response was negligible at best. It didn't prove American strength, but American weakness. I don't believe Bin Laden expected GWB to do anything about 9/11... and I don't believe Saddam truly believed the coalition of the willing would depose him. 12 years of dealing with America had taught the opposite lesson.