Staff writer Rick Atkinson describes the effort by the U.S. military to combat the improvised explosive devices used by insurgents in Afghanistan and Iraq from 2002 until Summer 2007. The series is drawn from more than 140 interviews over the past six months with military and congressional officials, contractors, scientists and defense analysts in Iraq, Afghanistan, Washington and elsewhere. Most agreed to speak candidly only on the condition of anonymity. Ten senior officers or retired officers, each of them intimately involved in the effort to combat IEDs, were asked to review the findings for accuracy and security considerations.