Out of the many volumes on Al-Qaeda out by now, the one here http://www.columbia.edu/cu/cup/catalog/idx_ltbook.html is the best I’ve seen. Concise (in 200 pgs. or so he summarizes a vast amt. of material on Al-Q cells from Sudan to Yemen) yet (The newish one by Jame Corbin of the BBC published here stateside by The Nation Books, on a cursory skim, is o.k. but, she has no background in terrorism studies.)
On the legitimation of violence in revolutionary discourse and practice see, “Humanism and Terror, “ by M. Merleau Ponty, for a sophisticated agument, as augmented by his counterpoint a decade later, “Adventures of the Dialectic, “ esp. the chapter, “Sartre and Ultra-Bolshevism, “ his reply to, “The Communists and Peace, “ a polemic against Claude Lefort, circa the Korean War and controversies that erupted after David Rousset’s book from the early 50’s on the Soviet camps. (All that is superbly narrated in Mark Poster’s book, “Existential Marxism in Post-War France, “ available in toto, online here, http://www.humanities.uci.edu/mposter/EM/ Michael Pugliese