Los Angeles Times: In a politically sensitive operation at the Arizona-Mexico border, U.S. Border Patrol agents and Mexican federal police officers are training together, sharing intelligence and coordinating patrols for the first time. The goal of the historic partnership: a systematic joint attack on northbound flows of drugs and migrants, and southbound shipments of guns and cash. It is part of a major, unannounced crackdown started in recent months involving hundreds of U.S. and Mexican officers in the border's busiest smuggling corridor.