I have heard a lot of questions about why Bush doesn't put his cards on the table as far as evidence is concerned. The obvious reason is that it compromises intelligence sources before we are prepared to act on the information.

It's possible that such a compromise would be bad for us even after a war has started, or after it has been won.

There is a lot of evidence to suggest that there are terrorist cells based in Iraq. When it all hits the fan, these cells will no doubt head across the borders to other nations like many Al Quaeda did in Afghanistan. If our sources are in these cells, they would "escape" with them, and remain useful even after a war with Iraq is won. If Saddam flees with his cronies, any sources inside that network would also flee with them.

This is only speculation on my part, of course. But given how easy it would be to reveal information and raise its credibility, the Bush administration must have a good reason for keeping this stuff under its hat.