A. To prove Sadam Hussein was not responsible for the Palestinian uprising. Sharon has now figured out the Palestinians are genuinely unhappy about the illegal settlements and were not simply the pawns of Hussein.
B. To prove Iraq had no weapons of mass destruction.
C. To get military parents out of the country so that impact aid (which is US money to school districts that serve military bases) could be reduced with out much noise from the parents (since they were now overseas).
D. To give Al Queda a much needed respite so that they can reorganize in Afghanistan.
E. To show North Korea they had better hurry up and get their nuclear weapons online to resist a US attack.
F. To show there are no documents to prove there was a link between Hussein and Al Queda
G. To give Halliburton yet more opportunities to rip off the US taxpayer by overcharging for gas and charging for meals not served to our soldiers, sailors, marines and airmen.
H. To prove the US CAN be wrong and the rest of the world correct.
I. To prove once again, that Intelligence is a very iffy proposition; just as was proved in the judgments about probable Soviet and Chinese reactions about our response to North Korea's invasion of South Korea; the Bay of Pigs, the "missile gap" of the 50s; the support among the Vietnamese for US intervention; etc. Once again we know that intelligence assessments should be looked at with a critical eye.
J. To prove there are limits to how far our military commitments can be extended.
K. To prove the long held Republican position that the US is not very good at "nation building"
L. And perhaps most importantly, to give jingoists the emotional high that is so similar to being from the high school with state champion football team.
To paraphrase Secretary Rumsfeld, sometimes smoke is only smoke.