World April 21, 2021 Vienna: The EU chief negotiator for the Iran nuclear deal talks said on Tuesday "much more hard work" was needed to save the 2015 landmark agreement, following the latest discussion round in Vienna. EU diplomat Enrique Mora hailed "progress made over the last two weeks" but said "ongoing challenges" remained to get the accord -- that curbs Iran’s nuclear programme in exchange for sanctions relief -- back on track. The deal was thrown into question when the US withdrew from it in 2018 and sanctioned Iran, which in turn started ramping up its nuclear activities. US President Joe Biden is seeking to revive the agreement.