By Louis Charbonneau and Arshad Mohammed
NEW YORK/WASHINGTON (Reuters) - U.S. Secretary of State John Kerry warned Iran ahead of this week's nuclear talks in Vienna that it has yet to prove that its nuclear ambitions are entirely peaceful in multiple rounds of talks with six world powers as a July 20 deadline nears.
Kerry made these remarks in an op-ed article published on the Washington Post website. The article appeared shortly after it emerged that U.S. Deputy Secretary of State Bill Burns is expected to attend the talks, which get under way on Tuesday.
The presence of Burns, who led secret negotiations between Iran and the United States that helped yield a November interim nuclear agreement with Tehran, would open up the possibility of bilateral talks between the two long-time antagonists.
In his op-ed, Kerry chided Iran by saying its "public optimism about the potential outcome of these negotiations has not been matched, to date, by the positions they have articulated behind closed doors."
"These gaps aren’t caused by excessive demands on our part," Kerry wrote, adding that the six powers had "showed flexibility to the extent possible."
The top U.S. diplomat said the July 20 deadline for a deal was "fast approaching".
Tehran, he suggested, can either seize the opportunity to do what is needed to ease concerns about its nuclear program or "they can squander a historic opportunity to end Iran’s economic and diplomatic isolation and improve the lives of their people.
"There remains a discrepancy, however, between Iran’s professed intent with respect to its nuclear program and the actual content of that program to date," he said.
PRESSURE ON IRAN?
Pressuring the Iranian delegation to change its negotiating stance may be one of Burns's goals this week. Western officials close to the talks say Tehran has yet to agree to sufficient curbs on the scale of its enrichment program, which is among the key sticking points in the negotiations.
Burns has met the Iranians twice in the last month, first in Geneva for bilateral talks, in an apparent effort to break a logjam between Tehran and major powers on the nuclear issue, and then in Vienna, where the wider nuclear talks take place.
During the latter talks, he broached the possibility of U.S. and Iranian cooperation to try to stabilize Iraq against an onslaught by Sunni militants.
The primary disagreement between the United States and Iran is over the Iranian nuclear program, which Washington and some of its allies suspect is designed to produce atomic weapons. Iran denies this, saying the program is for peaceful purposes.
The United States along with Britain, China, France, Russia and Germany, a group collectively known as the P5+1, and Iran reached an interim pact on Nov. 24 under which Iran won some relief from economic sanctions in return for reining in some of its nuclear activities.
Their target is to reach a comprehensive nuclear agreement that would lay to rest Western concerns about the Iranian program and comprehensively ease sanctions on Tehran by July 20, but outside analysts and diplomats are deeply skeptical they can achieve this.
The new round of talks starts on July 2 and will continue until at least July 15.
Western officials have said very little progress has been made, after five rounds of talks since February, toward striking a deal that could end years of hostility and defuse the risk of a new war and a nuclear arms race in the Middle East.
For the six powers, the overarching goal is to extend the time Iran would need to assemble an atomic bomb, if it chose to do so. To achieve this, they want Iran to cut the number of centrifuges in operation. Centrifuges are machines that purify uranium for use as fuel in atomic power plants or, if purified to a high level, weapons.
Both sides have said their goal is to have a deal by July 20 and avoid a difficult extension of the interim accord that expires then. Privately, Western diplomats say they would be willing to consider extending the interim deal and continuing talks beyond July 20 only if an agreement was clearly in sight.
(Reporting by Louis Charbonneau and Arshad Mohammed; Editing by Mohammad Zargham and Ken Wills)