U.S. Secretary of State John Kerry sought to bolster international support to keep pressure on Iran in nuclear talks with world powers set for Thursday even as Iran's new president pressed a diplomatic charm offensive at the United Nations.
The meeting in New York involves a very rare encounter between top officials of the United States and Iran. Iranian Foreign Minister Mohammad Javad Zarif will meet with Kerry as well as diplomats from Britain, France, Russia, China and Germany at a session aimed at jump-starting efforts to resolve a decade-long standoff over Iran's nuclear program.
Ahead of the session, Kerry said he looked forward to a "good meeting" but would not address what Iran needed to do to show a genuine desire to address its nuclear program.
The meeting with Zarif was set for 4 p.m EST.
Just hours before the start of the talks on the sidelines of the U.N. General Assembly, Kerry secured agreement from his Chinese counterpart calling for Iran to respond positively to existing nuclear proposals by the six world powers, U.S. officials said.
The U.S. comments suggested that President Barack Obama's administration intends to respond cautiously to Iranian President Hassan Rouhani's overtures, avoiding any major concessions unless Iran takes concrete steps to show it is serious about curbing its nuclear ambitions. Rouhani is seeking an easing of crippling international sanctions.
"Both the U.S. and China believe that Iran should cooperate with the P5+1 and should respond positively to the proposals that are on the table," a U.S. official said, referring to the six permanent members of the U.N. Security Council and Germany, often referred to as the P5+1.
The six powers said in February that they want Iran to stop enrichment of uranium to 20 percent, ship out some stockpiles and shutter a facility where such enrichment work is done. In return, they offered relief on international sanctions on Iran's petrochemicals and trade in gold and other precious metals.
Rouhani's gestures since taking office in August have raised hopes for a thaw in relations between Washington and Tehran after years of estrangement and for a resolution of the dispute on Iran's nuclear program.
A centrist cleric, Rouhani has stepped up efforts to moderate Iran's image abroad during a visit to New York. He said that Iran would never develop nuclear weapons - despite Western suspicions that it is seeking to do so - and called for a nuclear deal in three to six months. Iran has said its nuclear program is for peaceful energy purposes only.
Obama on Tuesday cautiously embraced Rouhani's gestures as the basis for a possible nuclear deal and challenged him to demonstrate his sincerity.
The failure to orchestrate a handshake between the two leaders, apparently due to Rouhani's concerns about a backlash from hardliners at home, underscored how hard it will be to make diplomatic progress.
Addressing a U.N. meeting on nuclear disarmament on Thursday, Rouhani said: "No nation should possess nuclear weapons, since there are no right hands for these wrong weapons."
But Rouhani also seized the opportunity to take a swipe at Iran's arch-foe Israel, which has accused him of trying to fool the world and buy time to continue its nuclear advances.
Rouhani said Israel, widely assumed to be the Middle East's only nuclear-armed state, was the reason for the failure of international efforts to establish the region as a nuclear weapons-free zone.
Asked what he needed to hear from the Iranians to show they were serious about addressing those concerns, Kerry, speaking to reporters as he began a meeting with China's foreign minister, replied: "I'll let you know after they've been serious."
Afterwards, a U.S. official said of the U.S.-China meeting: "They talked through the elements of the diplomatic track, as well as the sanctions track." Kerry also met with diplomats from Libya and Pakistan on Thursday.
European Union foreign policy chief Catherine Ashton, who is hosting the P5+1 meeting, met Rouhani earlier on Thursday, Ashton's spokesman said.
"What is certain is that there is a new will emerging both in Iran and among the P5+1 states to successfully conclude the new round of talks with a new approach," Abbas Araqchi, the Iranian deputy foreign minister, told Press TV, Iran's state-owned English-language broadcaster.
Thursday's meeting would be the first between a U.S. secretary of state and an Iranian foreign minister since a brief encounter in May 2007. The two countries have been estranged since Iran's 1979 Islamic Revolution that toppled the U.S.-backed Shah.
Iran has been negotiating with the P5+1 since 2006 about its nuclear program, which Western powers and their allies suspect is aimed at developing a nuclear-weapons capability.
Iranians are also hoping to see some concrete steps taken by the Western powers - namely relief from the painful U.S., European Union and U.N. sanctions for refusing to suspend its uranium enrichment program.
Additional reporting by Yeganeh Torbati, Lesley Wroughton and Louis Charbonneau at the United Nations and Marcus George in Dubai; Editing by Will Dunham