Iran demands the removal of the so-called snapback mechanism in its nuclear accord. The end of the treaty could revive all U.N. sanctions against Tehran, in the event of new talks with world powers, a senior aide to Supreme Leader Ayatollah Ali Khamenei said. Under the 2015 deal, Iran agreed to curb its nuclear work in return for relief from U.S. and other sanctions. The accord includes the option of a snapback of U.N. sanctions if Iran breaches the deal, requiring Tehran to suspend all nuclear enrichment-related and reprocessing activities, including research development. “This (trigger) mechanism must be abandoned as an irrational principle in the event of further negotiations,” Ali Akbar Velayati, a top adviser to Khamenei, said in an interview posted on the Supreme Leader’s website.