GAO Report: Firearms Trafficking to Mexico Hindered by Data Gaps

A new report from the Government Accountability Office reveals critical shortcomings in U.S. efforts to combat the flow of firearms to Mexican transnational criminal organizations (TCOs), hindering efforts to counter escalating cartel violence. The report, released September 28, 2026, details how TCOs are actively seeking semi-automatic rifles – including AR-15s, AK-47s, and .50-caliber rifles – which are often converted to fully automatic weapons and pose a significant threat to Mexican law enforcement and military forces.

The primary method of acquisition involves straw purchasers and middlemen who smuggle firearms across the U.S.-Mexico border. Data examined by the GAO indicates that from January 2020 to December 2024, 68 percent (82,785) of firearms recovered in Mexico and traced originated in the United States. U.S. Customs and Border Protection (CBP) seized 4,944 firearms bound for Mexico at land ports of entry between January 2020 and December 2025. However, the report highlights a critical data limitation: CBP’s systems do not consistently capture information on the specific types of semi-automatic rifles preferred by TCOs, and some officers struggle with accurate identification.

While multiple U.S. agencies – including CBP, Homeland Security Investigations, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), and the Department of State – are involved in combating firearms trafficking, the GAO found a lack of coordinated performance assessment. From fiscal years 2020-2025, ATF and the State Department’s Bureau of International Narcotics and Law Enforcement Affairs (INL) allocated approximately $126 million to these efforts. Despite this investment, DHS has not established measurable goals or performance indicators for its initiatives. ATF discontinued its performance measures in fiscal year 2023, and INL lacks baselines and results for some of its own measures. This absence of rigorous evaluation prevents agencies from determining the effectiveness of their programs and directing resources strategically.

The report underscores a critical vulnerability in border security and a potential impediment to broader U.S.-Mexico security cooperation, particularly given the recent designation of six Mexican cartels as foreign terrorist organizations in February 2025. Without improved data collection and performance monitoring, the U.S. risks inefficiently allocating resources and missing opportunities to disrupt the flow of firearms fueling cartel violence. The report's findings suggest that the current approach to combating firearms trafficking may not be effectively addressing the evolving tactics and capabilities of Mexican TCOs.