As for the idea of a smoking gun .. the Israeli's bombed a "suspected" nuclear facility created for developing the ability to make nuclear weapons. They did not have a smoking gun at the time. They were criticized at the time. Up until that time the International Atomic Energy Association had been giving Iraq flying colors for compliance to the non-proliferation treaty. While in truth the Iraqi's had a very active program going on to develop nuclear weapons.
After the Gulf War we found the smoking gun / the evidence that Iraq had been trying to develop nuclear weapons, that the facility that Israel hit was being used for the purpose. That if they had not hit it when they had in previous years that it was possible that Iraq would have had some nuclear weapons in 1991.
I personally don't like how Bush has tried to handle the diplomacy with other nations on this issue. I think it has been heavy handed and brutish. Would a few more months make a difference one way or another .. who know. But they have been trying to get him to comply since 1991. Nobody has said they believed Iraq has complied and has gotten rid of its WPM or the ability to produce them. They are just disagreeing about what to do about it. At some whether now or later somebody has to say enough is enough after 12 years.
I do agree with banana on this ... look at the history of the man and his regime. Look what they did try to develop, look how they used what they developed (they gassed Kurds and Iranian troops), look at their evasions in the 1970s, 1980s, 1990s, 2000s. Yes, Iraq has been marginalized and is not a conventional threat to us or probably even Iran or Saudi Arabia any more. However, think on the fact that a nuclear or biological weapon does not have to be delivered by a jet fighter but can be walked into a country. He has a history of using whatever means he has at his disposal to accomplish his goals and then trying to gain access to more deadlier weaponry.
Do we have a smoking gun .. no. Did the Israeli's no. Did Britain, France, and the world have a smoking gun on the holocaust in World War II. The gun was found afterwards.
The question is simple are we willing to gamble that if he ever does develop it and he was desperately trying that he won't use it or pass it on to another to use.