Encouraged by signs that Rouhani will adopt a more moderate stance than Ahmadinejad, but skeptical that the country's all-powerful supreme leader will allow a change in course, President Barack Obama has directed Kerry to lead a new outreach and explore possibilities for resolving the long-standing dispute.
Rouhani has come across as a more moderate face of the hard-line clerical regime in Tehran and his pronouncements at the U.N. have raised guarded hopes that progress might be possible. But they have also served as a reminder that the path to that progress will not be quick or easy.
He has steadfastly maintained that any nuclear agreement must recognize Iran's right under international treaties to continue enriching uranium.
The U.S. and its allies have long demanded a halt to enrichment, fearing Tehran could secretly build nuclear warheads. They have imposed sanctions over Iran's refusal to halt enrichment. Uranium enriched to low levels can be used as fuel for nuclear energy but at higher levels, it can be used to make a nuclear weapon.
Rouhani also insisted that any deal be contingent on all other nations declaring their nuclear programs, too, are solely for peaceful purposes — alluding to the U.S. and Israel.
Those conditions underscored that there is still a large chasm to be bridged in negotiations.
Rouhani has made a series of appearances and speeches since arriving in New York and has held bilateral negotiations with France, Turkey and Japan among others.
On Thursday, he called for worldwide disarmament of nuclear weapons as "our highest priority."
Speaking at the first-ever meeting of a U.N. forum on nuclear disarmament on behalf of the Non-Aligned Movement, an organization of mostly developing countries, Rouhani repeated the organization's long-standing demand that Israel join the international treaty banning the spread of nuclear weapons.
Israel, which has repeatedly accused Iran of aspiring to build a nuclear bomb, is the only Mideast state that has not signed the landmark 1979 Non-Proliferation Treaty.
Rouhani appears to be trying to tone down Ahmadinejad's caustic rhetoric against Israel — a point of friction in relations with the U.S. But Israel is not biting and reacted angrily to his latest remarks.
"Iran's new president is playing an old and familiar game by trying to deflect attention from Iran's nuclear weapons program," said Intelligence and International Affairs Minister Yuval Steinitz. "The problem of the NPT in the Middle East is not with those countries which have not signed the NPT, but countries like Iran, Iraq, Libya and Syria which have signed the treaty and brazenly violated it," he added.
"Unlike Iran, Israel has never threatened the destruction of another country," he said.
Iran watchers say Rouhani may have limited time to reach a settlement — possibly a year or less — before Khamenei decides negotiations are fruitless.
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