I believe you're correct.
I thought there was more than one letter to President Bush, but after further research, apparently I thinking of his terrorist rhetoric in other speeches.
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http://www.freerepublic.com/focus/f-news/1730468/posts?page=1487#1487
correction to post no. 1489: was thinking...
Technical Mujahid ~ New Periodic Magazine Related to Technology and Internet Security ....
Important item.....
The editors of the publication state that it was written to heed the directives of the Emir of al-Qaeda in Iraq, Abu Hamza al-Muhajir, and his call for technical support.