The day after one of Mexico’s most wanted drug lords, “El Mencho” (Nemesio Oseguera Cervantes), was killed in a dawn raid, Defence Minister Ricardo Trevilla Trejo said 80 percent of weapons seized from cartels have been smuggled across the border from the United States. With US intelligence help, Mexican forces tracked El Mencho to a property in Tapalpa; he led the Jalisco New Generation Cartel (CJNG), notorious for a military-style arsenal and rapid expansion. After his death on February 22, armed cartel members launched coordinated attacks on highways, police stations and rival territories across multiple states.
Main cartels and firepower
Mexico’s main cartels include the Gulf Cartel, the Sinaloa Cartel and the CJNG. They are heavily armed with military-grade rifles, high-capacity magazines and, in some cases, explosives. The CJNG is especially feared; it shot down Mexican military helicopters in 2015. Mexican and US authorities have rewards for several leaders, including Ismael Zambada Sicairos (“El Mayito Flaco”), Ivan Archivaldo Guzman Salazar (“El Chapito”), Fausto Isidro Meza Flores (“El Chapo Isidro”), and Juan Reyes Mejia-Gonzalez (“R-1” or “Kiki”), who carries a $15m US reward.
Mexican gun laws
Under Mexico’s Federal Law on Firearms and Explosives, civilians may legally buy only limited firearms (small handguns, .22 rifles and certain shotguns) and only through two military-run stores: DCAM in Mexico City and OTCA in Apodaca, Nuevo Leon. Purchasers face multiple approvals and background checks; military-grade rifles are reserved for the armed forces. Experts say cartels bypass these restrictions by sourcing most weapons illicitly, primarily from the US. Estimates put annual southbound trafficking from the US to Mexico at roughly 200,000 to 500,000 firearms.
How cartels obtain weapons
Cartels obtain weapons via straw purchasers (people who legally buy guns on behalf of others), unlicensed resellers, theft, corruption within security forces, and specialised brokers who source weapons and ammunition from US commercial markets. Straw purchasing violates the US Gun Control Act of 1968. Weapons are often transported overland in small, concealed shipments, sometimes disassembled. Since 2012, Mexico’s Defence Ministry said it seized 137,000 .50-calibre rounds from cartels; about half were traced to the Lake City Army Ammunition Plant in Missouri.
Legal and enforcement efforts
US federal law prohibits exporting firearms to non-US residents without ATF authorization, and Mexico forbids importing weapons without approval. In 2021 Mexico filed a $10bn lawsuit in US federal court against major US gun manufacturers (including Smith & Wesson, Beretta USA, Colt and Glock), arguing their practices facilitate illegal flows to cartels. The US Supreme Court, on June 5, unanimously ruled that the Protection of Lawful Commerce in Arms Act (2005) bars such claims because Mexico failed to show manufacturers “aided and abetted” illegal arms sales. Mexico has also sued five Arizona gun shops alleging they enabled straw purchases; that case is pending.
US operations and controversies
US authorities have run enforcement efforts to curb gun trafficking. From 2018 to 2021, the ATF’s Project Thor targeted US-based trafficking networks and brought dozens of cases; the programme was defunded in 2022. Earlier, Operation Fast and Furious (2009–2011) allowed more than 2,000 firearms to be illegally purchased and trafficked to track them to cartel leaders; many were lost and later used in violent crimes, including the killing of US Border Patrol agent Brian Terry in 2010. The operation drew severe criticism and accusations from Mexican officials that it violated sovereignty. Allegations have also surfaced (denied by US officials) that past counternarcotics strategies sometimes involved setting cartels against one another.
Is the US deliberately arming cartels?
Scholars say deliberate tactical arming of cartels by the US is unlikely. Benjamin Smith (University of Warwick) notes it’s possible US authorities turned a blind eye to certain trafficking to gain intelligence on one cartel, but there is no explicit policy to arm groups like the CJNG. Past incidents, such as weapons reaching criminal groups during Fast and Furious, are viewed as unintended consequences of enforcement strategies, not deliberate policy. Annette Idler (University of Oxford) argues access to US military-grade ammunition is better explained by market diversion and regulatory gaps than intentional US support.
What would counter gun trafficking?
Experts say countering southbound gun trafficking requires a major shift in US policy and priorities: treating firearms flowing to Mexico with the same urgency as drugs and people moving north, tightening oversight, investing in tracing and investigations, and framing cross-border security as a mutual obligation. Effective responses depend on sustained oversight, coordinated investigations, and deeper cooperation between the US and Mexico.