US President Barack Obama said a negotiated deal and not military action is the way to prevent Iran procuring nuclear weapons, in an interview broadcast on Israeli television on Monday.
"I can, I think, demonstrate, not based on any hope but on facts and evidence and analysis, that the best way to prevent Iran from having a nuclear weapon is a verifiable tough agreement," he told Channel 2, a private station.
"A military solution will not fix it, even if the United States participates. It would temporarily slow down an Iranian nuclear programme, but it will not eliminate it," Obama said.
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Asked if he was concerned Israel may attack Iran's nuclear facilities without consulting Washington in advance if Tehran strikes a deal with world powers, he declined to "speculate".
"What I can say to the Israeli people is I understand your concerns and I understand your fears," said the leader of Israel's closest ally.
Israel has been a fierce critic of a looming deal between Iran and world powers comprising the United States, Britain, China, France, Russia and Germany.
An accord targeted by the end of June would finalise an April 2 deal designed to prevent Tehran from developing nuclear weapons in exchange for an easing of crippling economic sanctions.
Israel says Iran can not be trusted to keep its word on a deal and has not ruled out the use of military force.