Iran agreed to come back to the negotiating table with six world powers, reviving hopes of a landmark nuclear deal.That's according to Iran's top nuclear negotiator after meeting with EU officials in Brussels.On Wednesday, Ali Bagheri Kani tweeted, "had a very serious & constructive dialogue with @enriquemora_ on the essential elements for successful negotiations. We agree to start negotiations before the end of November."Talks on Geneva had stalled after the election of Iran's hardline President Ebrahim Raisi in June.Raisi is expected to take a tougher approach with the west.Iranian foreign minister Hossein Amirabdollahian on Wednesday said U.S. President Joe Biden needed to demonstrate his commitment to negotiations.(SOUNDBITE) (Farsi) IRANIAN FOREIGN MINISTER, HOSSEIN AMIRABDOLLAHIAN, SAYING:“I personally believe that if Mr. Biden is serious, then he should show this so that we can believe that the Americans are actually serious about lifting sanctions.”Spearheaded by American diplomats in 2015, the Joint Comprehensive Plan of Action or JCPOA lifted global sanctions on Iran in exchange for limits on Tehran's nuclear program.Three years later, Republican President Donald Trump quit the deal and imposed new sanctions. Iran then resumed enriching uranium beyond limits set by the JCPOA.Under Democratic President Joe Biden, the U.S. has called for a return to the deal, but Iran has insisted on sanctions relief, first.U.S. Special Envoy for Iran Robert Malley said earlier this week that efforts to revive the pact were at a "critical phase" and Tehran's reasons for avoiding talks were wearing thin.