Negotiations over Iran's nuclear program may founder on one key issue, Vienna-based diplomats tell Science: whether Iranian researchers will be permitted to work side by side with Russians on uranium enrichment.
With Iran's referral to the U.N. Security Council looming as Science went to press, negotiators are pushing Iran to relinquish its right to enrich uranium. Under a Russian proposal, Russian centrifuges would boost the percentage of fissile uranium in Iranian hexafluoride gas. It's hoped that would deter Iran from using its own centrifuges to produce even higher percentages of fissile fuel for bombs. The plan, sources say, restricts Iranian scientists' presence at the facility to thwart leakage of knowledge that might accelerate Iran's alleged weapons program.
Iran has vacillated on the Russian proposal, and negotiations are expected to resume next week. Iran "will insist on learning more about enrichment technologies if the deal goes through," predicts Jack Boureston of nonproliferation research group FirstWatch International.
