Iran is moving to a point where it will have the ability to produce nuclear weapons, the U.S. State Department's senior adviser for non-proliferation and arms control said yesterday.
"We believe Iran is moving to the threshold of a nuclear weapons capability," Robert Einhorn said in response to a question at a Washington think-tank event.
Still, Einhorn said, the United States does not "see breakout as imminent at this stage."
Earlier in the day, world powers told Iran that "the door remains open" for dialogue on its disputed nuclear program, urging the Islamic Republic to cooperate with the United Nations atomic watchdog to resolve concerns it may have military aims.
The six powers leading negotiations with Iran issued a rare joint statement at a meeting of the International Atomic Energy Agency, in a bid to show unity and to step up pressure on Tehran after their talks with the Islamic state in December and January failed to make progress.
It was issued after IAEA Director General Yukiya Amano said on Monday that information his office recently received added to concerns about possible military aspects to Iran's atomic activities.
Amano voiced growing frustration at what the Vienna-based watchdog sees as Iran's failure to address allegations it may be working to develop a nuclear-armed missile.
The statement from the United States, Russia, Britain, France, Germany and China, also known as the 5 +1 group, called on Iran to cooperate with the agency.
"Outstanding issues need to be resolved in order to exclude the existence of possible military dimensions to Iran's nuclear program," they said in a statement.
It was the first joint statement by the big powers at the IAEA since March 2009.
Iran denies Western accusations it is seeking nuclear weapons capability, saying its atomic activities are aimed at generating electricity.
For several years, the IAEA has been investigating Western intelligence reports indicating Iran has coordinated efforts to process uranium, test explosives at high altitude and revamp a ballistic missile cone so that it can carry a nuclear warhead.
Iran, one of the world's biggest oil producers, says the allegations are based on forged documents.
The 5 +1 powers' statement said two rounds of talks with Iran in Geneva in December and in Istanbul in January did not reach any substantive result, despite their "constructive spirit" and practical ideas aimed at building confidence.
"We expect Iran to demonstrate a pragmatic attitude and to respond positively to our proposals and to our openness toward dialogue and negotiations," went the statement, read out by Russian Ambassador Grigory Berdennikov at the closed-door meeting of the IAEA's 35-nation governing board.
"The door remains open," the statement said.
The U.S. envoy to the IAEA, Ambassador Glyn Davies, made a separate statement to the board, about the "increasingly apparent military dimensions to Iran's nuclear program, including efforts by Iran to develop a nuclear warhead."
He urged Amano to report "promptly to the board his best assessment of whether there have been military dimensions to nuclear activities in Iran and, if so, whether he is in a position to verify they have stopped."
The UN Security Council has imposed four rounds of sanctions on Tehran since 2006 for refusing to freeze its uranium enrichment program.
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