Iranian officials said Russia’s demands at talks on Iran’s nuclear deal in Vienna are “not constructive”, Iran’s semi-official Tasnim news agency reported on Monday. Russia’s “interference” was aimed at securing its own interests, the agency cited unidentified Iranian officials as saying. Russia has demanded a US guarantee that the sanctions it faces over the Ukraine conflict would not hurt its trade with Iran. The demand could be a stumbling block in the talks. By postponing the revival of the agreement between Iran and the Western powers, and delaying Iran’s return to the oil market, Russia …