Iran Closes In on Ability to Build a Nuclear Bomb

Iraq did not have a bomb and was easily invaded, he said, while North Korea claims to have a bomb and is trying to use it as a bargaining chip with the U.S. for security assurances and possibly increased aid. "If a regime has the feeling that it is not on the right wavelength with the United States, its position is to have a nuclear weapon," he said.

Iran faces numerous technological obstacles before it can produce a nuclear bomb, according to intelligence officials and independent experts. Once those problems are solved or close to being solved, some experts said they expect Iran to withdraw from the nonproliferation treaty, as North Korea did, and close its doors to IAEA inspectors.

"They have made the decision to develop a breakout capability, which will give them the option to leave the treaty in the future and complete a nuclear weapon within six months or a year," said Gary Samore, director of nonproliferation programs at London's International Institute for Strategic Studies and a former Clinton administration security official. "I think the program is probably unstoppable through diplomatic means."

Others disagree.

"I don't believe they have passed the point of no return," said Perkovich, the nuclear weapons expert at the Carnegie Endowment. "We should try to reverse Iran's direction by providing better, low-cost options to fuel the Bushehr electricity plant and by easing the security concerns that make Iranians, reformers and hard-liners, interested in getting a bomb."

Diplomacy has proved an imperfect solution in the past. The Clinton administration persuaded China not to sell nuclear items to Iran in the mid-1990s. Administration officials later used sanctions and negotiations to convince Russia to curb technology transfers to Iran's civilian program that U.S. intelligence believed were being diverted to weapons work.

But Russia is committed to the Bushehr reactor, which generates 20,000 jobs for its beleaguered nuclear industry. The project also allows hundreds of Iranians to train in Russia, raising concerns within the intelligence community that knowledge and hardware for weapons work will slip through.

Officials in Moscow, outside experts and foreign intelligence officials said economics are driving continuing Russian assistance to the Iranian weapons program and that it is probably occurring without government approval. They said thousands of Russian physicists, mathematicians and other scientists are unemployed or paid a pittance at home, pushing them to sell their expertise elsewhere.