` ` We have identified all of the issues we need to address '' for final approval , says Ashton . The next round of talks will begin on September 17 , Iranian foreign policy chief says . Wendy Sherman , a senior State Department official and lead negotiator for the United States on the interim deal , told CNN 's Wolf Blitzer from Vienna this week that any final agreement will be contingent on Iran taking `` concrete '' verifiable steps that prevent it from ever obtaining a nuclear weapon . U.S. State Department spokesman says talks have been ` ` constructive and useful '' Western powers suspect Iran wants to develop a nuclear weapon , a claim it denies .
` ` We have identified all of the issues we need to address '' for final approval , says Ashton . The next round of talks will begin on September 17 , Iranian foreign policy chief says . U.S. State Department spokesman says talks have been ` ` constructive and useful '' Western powers suspect Iran wants to develop a nuclear weapon , a claim it denies .