Stephen Ulph, an analyst at the US-based Jamestown Foundation, said the letter presented a number of problems. There had been no clarification as to how it was intercepted and no independent corroboration of its authenticity. He also found it remarkable that a letter between two al-Qaeda leaders should spell out strategy in such an explanatory way, as if these basic details were the subject of doubt.

And here are still more people who don't buy it...