United Nations Looks Closely at Iran's Nuclear Program

After challenging Iran’s atomic efforts with everything from diplomatic crusades to shows of military force, the Americans backed off late last year, based on a new intelligence finding that Tehran had suspended work in late 2003 on the design of nuclear arms. Now, in the waning days of President Bush’s second term, it would be difficult — politically, diplomatically and militarily— for them to try to press for a new confrontation.

But early this year, Washington also turned over a trove of its own intelligence to the atomic investigators in Vienna, who put it together with clues gathered from many foreign capitals and findings from their own long years of inquiries.

On the basis of that combination of new and old evidence, over the last few months, the inspectors of the International Atomic Energy Agency have come to worry that Iran — before suspending its work nearly five years ago — may have made real progress toward designing a deadly weapon.