Those tubes became a critical exhibit in the administration's brief against Iraq. As the only physical evidence the United States could brandish of Mr. Hussein's revived nuclear ambitions, they gave credibility to the apocalyptic imagery invoked by President Bush and his advisers. The tubes were "only really suited for nuclear weapons programs," Condoleezza Rice, the president's national security adviser, explained on CNN on Sept. 8, 2002. "We don't want the smoking gun to be a mushroom cloud."
But almost a year before, Ms. Rice's staff had been told that the government's foremost nuclear experts seriously doubted that the tubes were for nuclear weapons, according to four officials at the Central Intelligence Agency and two senior administration officials, all of whom spoke on condition of anonymity. The experts, at the Energy Department, believed the tubes were likely intended for small artillery rockets.
The White House, though, embraced the disputed theory that the tubes were for nuclear centrifuges, an idea first championed in April 2001 by a junior analyst at the C.I.A. Senior nuclear scientists considered that notion implausible, yet in the months after 9/11, as the administration built a case for confronting Iraq, the centrifuge theory gained currency as it rose to the top of the government.
Senior administration officials repeatedly failed to fully disclose the contrary views of America's leading nuclear scientists, an examination by The New York Times has found. They sometimes overstated even the most dire intelligence assessments of the tubes, yet minimized or rejected the strong doubts of nuclear experts. They worried privately that the nuclear case was weak, but expressed sober cer ude in public