U.S. law enforcement agencies have built up networks of Mexican informants that have allowed them to infiltrate some of that country's most powerful and dangerous criminal organizations, reports the New York Times. Informants have helped Mexico capture or kill two dozen high-ranking and midlevel traffickers, and sometimes have given U.S. counternarcotics agents access to leaders of cartels they are trying to dismantle.
Mexico is kept in the dark about U.S. contacts with its most secret informants partly because of concerns about corruption among Mexican police, and partly because of laws prohibiting American security forces from operating on Mexican soil. “The Mexicans sort of roll their eyes and say we know it's happening, even though it's not supposed to be happening,” said Eric Olson of the Woodrow Wilson Center. Mexican attitudes about American involvement in matters of national security have softened, as drug-related violence has left 40,000 people dead. The efforts are credited with breaking up some of Mexico's largest cartels into smaller — and presumably less dangerous — crime groups.