US Secretary of State John Kerry (L) and Iranian Foreign Minister Mohammad Javad Zarif shake hands prior to a bilateral meeting of the closed-door nuclear talks with Iran at the Palais Coburg in Vienna on November 23, 2014.Iran and world powers engaged Sunday in a last-ditch diplomatic blitz to nail down a nuclear deal in less than 36 hours, with Tehran signalling it is open to extending talks by up to a year. AFP PHOTO / POOL/ RONALD ZAK (Photo credit should read RONALD ZAK/AFP/Getty Images)
