Yet, of the Americans who died last week in the suicide bombing at the CIA’s most sensitive outpost in Afghanistan, it is the seventh whose presence has raised the most urgent questions as the US scrambles to repair — and avenge — the damage done to the hunt for Osama bin Laden. According to a security official in Kabul with close ties to the CIA, when Humam Khalil Abu-Mulal al-Balawi carried out his deadly mission at Forward Operating Base Chapman, he managed to kill the agency’s deputy head of station for the whole of Afghanistan. The senior agent was waiting...