Iran Plans Defense of Nuclear Program

But the Bush administration said the 2000 commitments, which did not focus on terrorism, a changed Middle East or a nuclear black market, are not relevant in a world altered by the attacks on the United States a year later on Sept. 11, 2001.

Most critics of the administration's position agree that some of the commitments are outdated and say the unilateral decision to walk away from a set of ideas adopted by consensus weakens the treaty and the U.S. position.

"If the conference fails and the U.S. is seen as the reason for that failure, it is going to be much harder for the United States to get the international cooperation it needs to deal with Iran, to deal with North Korea and to deal with all the other issues we are concerned about," said Joseph Cirincione, a nuclear expert at the Carnegie Endowment for International Peace.

Cirincione said U.S. research into new nuclear weapons and new uses for nuclear weapons, coupled with a refusal to ratify a treaty banning nuclear testing, has led countries to doubt the U.S. commitment to the treaty. He said the United States must lead by example if it expects others to sustain their pledges.

But the Bush administration has rejected that argument.

"This notion that the United States needs to make concessions in order to encourage other countries to do what is necessary to preserve the nuclear nonproliferation regime is at best a misguided way to think about the problems confronting us," Stephen G. Rademaker, assistant secretary of state for arms control, said in congressional testimony last week.

Rademaker, who was named to lead the U.S. delegation to the conference, said the United States would use the meeting to focus on Iran's alleged noncompliance with the treaty and North Korea's withdrawal from the agreement.

European officials have been concerned about U.S. aims at the conference, saying a toughly worded speech or narrow focus on Iran could inflame rather than alleviate tensions at a sensitive time in their negotiations with Tehran. "The last thing we want is an inflammatory speech from either side," one senior European official said.

Zarif said Iran plans to be firm on its rights under the treaty despite the suspicions. "An attempt to make compliance the central issue of this conference is a smoke screen designed to conceal the fact that there were decisions taken at the previous conference, and adopted by consensus, for disarmament," he said. "We know our rights."