Tensions in the nuclear talks between Iran and six powers have boiled over in recent days, producing heated exchanges among foreign ministers as Washington and Tehran struggled to overcome remaining hurdles to a final agreement, according to people involved in the talks. The German and British foreign ministers returned to the Austrian capital Wednesday evening as Western diplomats insisted a deal was still possible in coming days. However, time was running out for the agreement to be sealed before a deadline this week which would give the U.S. Congress an extra month to review a deadline. People close to the talks have warned that the longer Congress and opponents of the diplomacy get to pick over an agreement and galvanize opposition, the greater the political risks for supporters of the process, which aims to block Iran’s path […]