Diplomats from world powers and Iran wait for the start of a meeting of the JCPOA Joint Commission in Vienna, Austria, on Tuesday. EU DELEGATION IN VIENNA/XINHUA Negotiators to push on in bid to narrow gap, as China urges US to end sanctions VIENNA－Iran and world powers held what they hailed as "constructive" talks on Tuesday in Vienna, paving the way for teams to discuss the compromises required by Washington and Teheran if they are to revive a landmark 2015 nuclear deal. It was agreed that working groups from the signatories to the pact will discuss the sanctions the United States might lift and the nuclear curbs Iran might observe to refloat the deal.