Overview: Day after day scores of bodies litter the streets of Baghdad. To staunch the violence, the U.S. has spent billions to "stand up" the Iraqi forces. In Gangs of Iraq, a joint production of FRONTLINE and the "America at a Crossroads" series, FRONTLINE takes a hard look at how the four-year training effort has fared and how the coalition-trained forces have themselves been infiltrated by various sectarian militias. Now, with President Bush sending new U.S. troops to Iraq, it remains to be seen if America and its allies can build a national Iraqi army and police and restore order.