U.S. Secretary of State John Kerry reacts as he delivers a statement on the Iran talks deal at the Vienna International Center in Vienna, Austria July 14, 2015. Iran and six major world powers reached a nuclear deal on Tuesday, capping more than a decade of on-off negotiations with an agreement that could potentially transform the Middle East, and which Israel called an "historic surrender". REUTERS/Leonhard Foeger
VIENNA (AP) — As both sides warned against high expectations, Iran and six world powers began talks Tuesday on a comprehensive nuclear deal, trying to overcome deep differences about how much Tehran needs to scale back its atomic program in exchange for an end to crippling economic sanctions.
The talks are to build on a first-step deal that came into effect last month and commits Iran to initial curbs on its nuclear program in return for some easing of sanctions.
Iran insists it is not interested in producing nuclear weapons but the six powers want Tehran to back its words with concessions. They seek an agreement that will leave Iran with little capacity to quickly ramp up its nuclear program into weapons-making mode with enriched uranium or plutonium, which can used for the fissile core of a missile.
For that, they say Iran needs to dismantle most of its 20,000 uranium enriching centrifuges, including some of those not yet working. They also demand that an Iranian reactor now being built be either scrapped or converted from a heavy-water setup to a light-water facility that makes less plutonium.
Iran is fiercely opposed to any cutbacks but it's also desperate to shed nearly a decade of increasingly strict sanctions on its oil industry and its financial sector. Influential conservatives in Iran and the United States who are skeptical of offering too much are further complicating the talks.
The talks are formally led by Catherine Ashton, the EU's top foreign policy official, and Iranian Foreign Minister Mohammad Javad Zarif. The United States, Russia, China, Britain, France and Germany are also at the table.
Ashton spokesman Michael Mann warned of the "intensive and difficult work lying ahead of us."
Iranian Deputy Foreign Minister Abbas Araghchi said the talks got off to a "very good beginning." He said even if they end later this week with nothing more than a future agenda "we've accomplished a lot."
Margaret Childs contributed.