Iran nuclear talks stumble, but meetings in Geneva continue But the negotiators" earlier confidence appeared to have faded, as diplomats traded barbs in television interviews and warned of significant gaps between the sides. Iran's second-ranking official present at the talks said his delegation had "lost our trust" in its negotiating partners, because of changes in the terms of the proposed agreement offered by the so-called P5-plus-1 powers (the United States, Britain, China, France, Germany and Russia). "We cannot enter serious talks until the trust is restored," Iranian Deputy Foreign Minister Abbas Araghchi told reporters during a pause between sessions. That doesn't mean that we will stop negotiations. France's chief diplomat, Foreign Minister Laurent Fabius, also sounded a pessimistic note, telling France 2 television that any deal could "only be possible based on firmness" and hinting that Tehran had not yet met the test. Despite the verbal jousting, a European Union spokesman described Thursday's meetings as "substantial and detailed." The talks included a private session between E.U. foreign policy chief Catherine Ashton and Iranian Foreign Minister Mohammad Javad Zarif. The tone of the meeting was soured, in part, by public comments Wednesday by Iran's supreme leader, Ayatollah Ali Khamenei, who referred to Western countries as "evil powers" and called Israel the "rabid dog" of the Middle East. The Obama administration brushed off the remarks and insisted that a proposed deal to curb Iran's disputed nuclear program is not the trap that Israel fears. "We have the best chance we've had in a decade, we believe, to halt progress and roll back Iran's program," Secretary of State John F. Kerry said in Washington. He said the United States would not allow an agreement, should one be reached, to "buy time" for Iran to make progress toward a weapons program or to fall short of "our core fundamental concerns."