The Sun article implies multiple sources. I have no idea if any of it is true. Ledeen's post on the Corner indicates he finds it credible, but he also implies that it could be the result of ritual chest-beating by one or more mullah factions in a domestic power dispute. Or something else, including sheer hubris.
One thing we cannot count on from the Bush administration is any degree of common sense or connection with reality - its actions on the immigration bill prove that.
The Sun is a tabloid and they are using, supposedly, anonymous sources and Ledeen’s hunches have been wrong before.