The United States is pouring billions more dollars and fresh platoons of experts into its campaign to “defeat IEDs,” the roadside bombs President Bush describes as threat No. 1 to Iraq’s future. The American military even plans to build special, more defensible highways here, in its frustrating standoff with the makeshift munitions — “improvised explosive devices” — that Iraqi insurgents field by the hundreds to hobble U.S. road movements in the 3-year-old conflict. Out on those risky roads, and back at the Pentagon, few believe that even the most advanced technology will eliminate the threat. Full Story