A lot of ink will be spilled on President Bush's apparent involvement in the leaking of parts of the National Intelligence Estimate on Iraq. We will be on top of that here at Passport. But right now, there's a point worth keeping in mind: Don't let the focus on yellowcake obscure the fact that the aluminum tubes claim was much more important (breakdown). As Jofi Joseph argued here: 

In the fall of 2002, the aluminum tube claim was the top administration talking point as President Bush made his case for war to the U.S. Congress and the United Nations. Yellowcake wasn’t really in the picture until well after Congress voted to authorize the use of force. Iraq already possessed considerable amounts of uranium and other materials required to make nuclear bombs, so an additional purchase from Africa wouldn’t make much of a difference. Without the aluminum tubes, however, Iraq could not enrich that uranium to weapons-grade fissile material.