actually they all had access to the same information. furthermore, the claims about Saddam's WMD programs pre-existed the Bush administration, and were part of the Clinton Administrations decision to change U.S. policy to that of regime change
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I don't recall the mushroom clouds (i recall a lot about chem/bio and some about dirty bombs), but no, it wasn't pure B.S. Firstly because we found both uranium and chemical weapons in Iraq, and Secondly because it was the opinion of the IC that there were active production lines ongoing in Iraq at the time, protected by a significant (and previously successful) D&D campaign by a regime skilled in that technique. And not just our own IC, but that of our allies and even our not-so-allies.
I realize that's a handy bumper sticker. It merely lacks what Henry Kissinger used to call "the added benefit of being true".