Bangladesh, Sept. 30 -- For years, drug traffickers have relied on clandestine air routes to move cocaine from Venezuela to the United States, bypassing maritime patrols and land-based interdictions. Now, a series of leaked emails from Mexicos defense ministry has shed light on an overlooked element of that trafficking network: private jets regularly ferrying narcotics into Belize, a small Central American nation long considered peripheral to the regional drug trade.

The documents – part of a trove of hacked correspondence obtained by the activist group Distributed Denial of Secrets and shared with the Organized Crime and Corruption Reporting Project (OCCRP) – reveal at least 70 alerts issued by US authorities to their Mexica...