Washington said Wednesday it was “close” to a deal with Iran on reviving a 2015 pact that saw Western powers provide sanctions relief in exchange for curbs on Tehran’s nuclear programme, the latest sign of advancement following prolonged deadlock. Days after Russian demands seemed to jeopardise talks in Vienna over restoring the pact, this week has seen multiple positive signals that an accord may at last be within reach, including the release of two British Iranians Wednesday after years of detention in Iran, and word that outstanding issues have narrowed to just two. The negotiations began l…