The United States on Monday appeared to dismiss a key Iranian demand to salvage a nuclear accord as Tehran blamed Washington for the prolonged impasse. Iran and the United States have been negotiating indirectly in Vienna for a year to restore the 2015 agreement, known formally as the Joint Comprehensive Plan of Action, from which former US president Donald Trump withdrew. One key sticking point is Iran’s insistence on removing the US designation made by Trump that the Revolutionary Guards, the clerical regime’s elite military unit with broad reach in the economy, is a terrorist organization. …