The transience of Afghan extremist networks involved in the making and emplacing of improvised explosive devices is posing new challenges for the cadre of U.S. military officials charged with disabling these groups, a Defense Department official told InsideDefense.com today. Unlike in Iraq, where officials had identified "five or six" national-level extremist groups attacking coalition forces with IEDs, in Afghanistan clearly defining and counting such groups is "impossible," said Kenneth Comer, who is director of the Operations Research Systems Analysis Division...