Russia's foreign minister says there is no evidence Tehran has made the "political decision" to produce nuclear weapons but almost certainly would do so if Iran were attacked.
In a Russian radio interview, Sergei Lavrov also criticized Iranian President Mahmud Ahmadinejad for threatening to destroy Israel in the past.
"This is completely unacceptable," Lavrov said.
Lavrov also said that Moscow is concerned by reported U.S. plans to maintain military bases in Afghanistan and Central Asia after the scheduled 2014 withdrawal of NATO forces from Afghanistan.
"We would like to know what is the goal of this presence," Lavrov said, adding that such bases could be "used against third countries."
He also said the leader in any negotiations with the Afghan Taliban should be the Afghan government, not the United States.
Outgoing President Dmitry Medvedev on March 20 issued a fresh call
for Russia's military to be "fully prepared" and "fully armed" by 2017-18 to counter U.S. plans to erect a missile-defense system in Europe. U.S. officials have said the aim of its European missile-defense system is to guard against attack by rogue states, including Iran.
With Interfax and AFP reporting