I have never been very impressed with 4GW theory and find myself in agreement with Echevarria's assessment. If one is interested in some innovative thinking on the subject a recent book, Networks, Terrorism, and Global Insurgency, edited by Robert Bunker and published by Routledge (originally as special issue of Low Intensity Conflict & Law Enforcement - Vol 11 No 2/3 Winter 2002). Of particular interest is the lead chpter/article of Part Three, "Challenging the Hegemon: Al Qaeda's Elevation of Asymmetric Insurgent Warfare Onto the Global Arena" by Kimbra L. Fishel.