REUTERS/Mahmoud Raouf Mahmoud (IRAQ) Disguises Used in Attack on Troops Gunmen Infiltrated Secured Iraqi Site, Killing 5 Americans By Ernesto LondoƱo Washington Post Staff Writer Monday, January 22, 2007; Page A01 BAGHDAD, Jan. 21 -- The armored sport-utility vehicles whisked into a government compound in the city of Karbala with speed and urgency, the way most Americans and foreign dignitaries travel along Iraq's treacherous roads these days. Iraqi guards at checkpoints waved them through Saturday afternoon because the men wore what appeared to be legitimate U.S. military uniforms and badges, and drove cars commonly used by foreigners, the provincial governor said. Once inside, however, the men unleashed one of the deadliest and most brazen attacks on U.S. forces in a secure area. Five American service members were killed in a hail of grenades and gunfire in a breach of security that Iraqi officials called unprecedented. The attack, which lasted roughly 20 minutes,...