Saddam probably could not hurt the United States directly with a bomb even if he had one. Even if he overcomes his most serious obstacle by obtaining fissile material on the black market, he would probably be able to build only a few nuclear weapons, and they would be big. That would make it hard to transport such weapons to give to terrorists or his own foreign-based operatives for use against a U.S. city. He might be able to sneak a bomb into Kuwait or another neighboring state with a low-flying aircraft, but the plane might well also get shot down. He probably does not have a missile big enough to carry what would be a fairly primitive and thus large nuclear warhead.
which tends to undercut most of the worst-case scenarios of a mushroom cloud over New York promoted by pro-attack pundits, who have a "marked propensity to assert as fact points for which there is virtually or absolutely no evidence".
note that the (Bush Administration) claim that Saddam has recently been buying thousands of aluminum tubes for uranium centrifuges is itself under suspicion. And the main Iraqi weapons scientist who defected, Dr. Khidhir Hamza, has a credibility issue, given that his booking agent has ties to warmongering thinktanks.
That said, does it make any sense for the Bush Administration to BLOCK weapons inspectors from going to Iraq?