An understanding is emerging between Iran and six major powers that a final nuclear deal between the two sides must be structured around a key demand of the U.S. and its European partners: that Tehran stay at least a year away from amassing enough fuel for a nuclear weapon, according to people familiar with the negotiations. The understanding about Iran’s so-called breakout time, if it can be nailed down as part of a broader package, could open the way to a final nuclear agreement in coming weeks, although diplomats warned again on Wednesday that difficult obstacles remained in the way of a deal. The breakout period has been one of the critical questions in the talks. Last year, negotiations […]