ISLAMABAD: A Pakistan-led initiative to facilitate US-Iran talks has been held up, with Tehran yet to formally respond to proposals for dialogue despite back channel exchanges in recent days, a senior official told Dawn on Friday. The official, who was speaking on background, said some ground had been covered, with messages relayed between Washington and Tehran, but the absence of a clear Iranian signal has slowed momentum at this critical stage. “It is surprising that despite the obliteration o...