Possibly not. A friend e-mails:
“The Islamic year is shorter than the Gregorian year. 2001 September 11 was 1422 Jumada t-Tania 22 in the Islamic Calendar. Corresponding to 1427 Jumada t-Tania 22 was 2006 July 19. So if the attackers use the Islamic calendar, a fifth anniversary attack would already have happened. I knew that the Islamic year was shorter than the Gregorian year when I got my first almanac in the sixth grade. But no one in the entire Federal security apparatus knew this and warned our country of a possible first anniversary attack on 2002 August 31. So we were quite unprepared, even though the attack never took place.”
[Derb] Well, I guess he has a point. However, if the terrorists are going for psychological effect, which they surely are, they might make a point of picking OUR fifth anniversary, not THEIRS.