US officials have blamed Britain for an embarrassing fiasco in which an impostor met Afghan and Nato officials before it was discovered he was not the Taliban leader they thought he was, according to sources familiar with the incident. It was revealed this week that the man – understood to be a shopkeeper from the Pakistani city of Quetta – was masquerading as Mullah Akhtar Muhammad Mansour, the second highest-ranking official in the Taliban. He attended three meetings in Kabul. The New York Times columnist Maureen Dowd reported today that people familiar with the con – as she described it...