(VOVworld) – US Secretary of State John Kerry and Iranian Foreign Minister Javad Zarif resumed Tuesday in Switzerland talks on Iran’s nuclear program as the deadline for a framework deal approaches. Six world powers, the US, Germany, France, Britain, Russia and China, are trying to make a deal with Iran that would curb Iran's most sensitive nuclear activities for at least 10 years in exchange for the gradual easing of some sanctions. Analysts hope Iran and the US can make a giant leap in building mutual trust, but differences remain. Iran says it will maintain its nuclear program for peaceful purposes, which western countries doubt. Negotiations are trying to reach a final framework deal by March 31^st and a comprehensive agreement by June 30^th, after missing two previous deadlines.