President Barack Obama has defended a framework nuclear agreement with Iran as a "once-in-a-lifetime opportunity" to prevent a nuclear bomb and bring longer-term stability to the Middle East.
He insisted the US would stand by Israel if it were to come under attack, but acknowledged that his pursuit of diplomacy with Tehran has caused strain with the close ally.
"It's been a hard period," Obama said in a weekend interview with The New York Times published on Sunday.
He added that it is "personally difficult" for him to hear his administration accused of not looking out for Israel's interests.
Now in his seventh year in office, Obama cast the Iran talks as part of a broader foreign policy doctrine that sees American power as a safeguard that gives him the ability to take calculated risks.
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"We are powerful enough to be able to test these propositions without putting ourselves at risk," he said, citing his overtures to Cuba and Myanmar as other examples of his approach.
The president's comments come days after the US and other world powers reached a tentative agreement to curb Iran's nuclear program in exchange for sanctions relief. The framework cleared the way for negotiators to work out technical details ahead of a June 30 deadline for a final deal.
Obama argued that successful negotiations presented the most effective way to keep Iran from obtaining a nuclear weapon, but insisted he would keep all options on the table if Tehran were to violate the terms.
"I've been very clear that Iran will not get a nuclear weapon on my watch, and I think they should understand that we mean it," Obama said.
"But I say that hoping that we can conclude this diplomatic arrangement - and that it ushers a new era in US-Iranian relations - and, just as importantly, over time, a new era in Iranian relations with its neighbours."
