Adrian: The US has explained nothing officially. However, we now know more than ever before, having talked to Lashkar, the intelligence communities in five countries, and countless diplomats and jihad outfits, what Headley's role was and the game he played. At that time Headley was moving away from Lashkar and towards Al Qaeda, as Lashkar began to split. That move, towards Ilyas Kashmiri and others, made Headley the nearest thing to a bridge to Osama. That was tantalizing for anyone in US and Western intelligence with an interest in tracking Osama. A terrible call was made, a narrow self interested one, to allow Headley to run on, with the promise that bin Laden might be captured and Mumbai was, in one sense, sacrificed along the way.