Firearms Trafficking to Mexico: Better Data and Performance Monitoring Would Help Agencies Direct Resources to Counter Cartels
Fast Facts
Thousands of firearms are smuggled from the U.S. into Mexico each year by transnational criminal organizations—threatening security in both countries.
The Departments of Homeland Security and State and the Bureau of Alcohol, Tobacco, Firearms and Explosives combat this by, for example, inspecting southbound vehicles at the border and providing security assistance to the Mexican government.
But while these agencies report the results of these efforts—such as the number of guns seized—they don't measure their effectiveness. For instance, they haven't all established goals and performance measures for their efforts.
We recommended they do so.
Customs and border patrol patch on the sleeve of an officer standing outside with a pickup truck in the background.
Highlights
What GAO Found
Transnational criminal organizations (TCO) in Mexico seek to acquire semi-automatic firearms—AR-15s, AK-47s, and .50-caliber rifles—which they often convert to fully automatic firearms, according to agency officials. Armed with these weapons, TCOs pose a serious threat to Mexican law enforcement and military. TCOs acquire firearms from the U.S. primarily through straw purchasers—third parties who buy them on the TCOs’ behalf—and middlemen who smuggle the firearms through ports of entry on the border.
U.S. agencies collect data on trafficked firearms, but some data have limitations that limit their utility. The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) reported that 68 percent (82,785) of firearms recovered in Mexico and traced from January 2020 to December 2024 had a U.S. source. Department of Homeland Security (DHS) U.S. Customs and Border Protection (CBP) data show that CBP seized 4,944 firearms bound for Mexico at land ports of entry on the border from January 2020 through December 2025. However, CBP’s data system does not consistently capture information on the semi-automatic rifles sought by TCOs, and some officers may have difficulty identifying specific types. Improved data on these types of rifles would strengthen federal agencies’ ability to generate intelligence to combat firearms trafficking from the U.S. to Mexico.
U.S. agencies conduct various efforts to combat firearms trafficking but do not assess effectiveness. For example, in the U.S., CBP conducts targeted outbound inspections along the U.S.–Mexican border and DHS’s Homeland Security Investigations and ATF seek to disrupt firearms trafficking along the border. In Mexico, ATF helps Mexican authorities conduct investigations and trace firearms. The Department of State’s Bureau of International Narcotics and Law Enforcement Affairs (INL) provides security assistance to Mexican authorities to combat firearms trafficking. In fiscal years 2020–2025, ATF and INL provided about $126 million for these efforts. But DHS has not established goals, desired outcomes, or performance measures that include baselines and targets for its efforts. ATF also lacks performance measures, after discontinuing measures it established in fiscal year 2023, and INL lacks baselines, targets, and results for some of its measures. As a result, the agencies do not know the extent to which their efforts are meeting objectives and cannot determine whether they are directing resources to the most effective programs. This could lead to waste and, potentially, missed opportunities to more effectively counter firearms trafficking.
Vehicle Inspected, Hidden Compartment, and Firearms Seized at U.S.–Mexican Border
Why GAO Did This Study
Estimates indicate that hundreds of thousands of firearms are trafficked from the U.S. into Mexico each year, presenting a serious threat to Mexican and U.S. security. TCOs in Mexico use increasingly deadly firearms as well as technology and drones. In February 2025, State designated six Mexican cartels as foreign terrorist organizations and as specially designated global terrorists.
GAO was asked to review U.S. efforts to combat firearms trafficking to Mexico. This report examines (1) the types of firearms TCOs in Mexico seek in the U.S. and the methods they use to illegally acquire and transport them into Mexico; (2) data U.S. agencies have collected on Mexico-bound firearms seized in the U.S. and on U.S.-sourced firearms recovered in Mexico, as well as the agencies’ uses of these data; and (3) efforts that U.S. agencies have made to combat firearms trafficking to Mexico, as well as the extent to which they have monitored these efforts’ performance. GAO reviewed agency documents and interviewed U.S. officials in Washington, D.C.; El Paso, Dallas, and Houston, Texas; and Nogales, Tucson, and Phoenix, Arizona. GAO also interviewed U.S. and Mexican officials at the U.S. embassy in Mexico City. GAO analyzed CBP data on seizures of southbound firearms at the U.S.–Mexican border in 2020–2025 as well as ATF data on firearms recovered in Mexico and submitted to ATF for tracing in 2020–2024.
Recommendations
GAO is making four recommendations to DHS, ATF, and INL. The agencies agreed with three recommendations to improve performance management. DHS disagreed with a recommendation to improve data collection. GAO maintains that this recommendation is valid.
Recommendations for Executive Action
| Agency Affected | Recommendation | Status |
|---|---|---|
| Department of Homeland Security | The Secretary of Homeland Security should ensure that the Commissioner of CBP takes steps to record readily analyzable data on the types of firearms—particularly types of rifles sought by TCOs in Mexico—seized during CBP outbound inspections. Such steps could include modifying CBP's current data collection system, such as by making certain optional fields required or adding drop-down options, or by providing training or guidance in the identification of specific types of firearms. (Recommendation 1) |
When we confirm what actions the agency has taken in response to this recommendation, we will provide updated information.
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| Department of Homeland Security | The Secretary of Homeland Security should ensure that the Director of U.S. Immigration and Customs Enforcement and the Commissioner of CBP develop objectives, goals, and desired outcomes to enable the department to establish corresponding performance measures for HSI's and CBP's efforts to combat firearms trafficking from the U.S. to Mexico. DHS could do so by updating its strategic plan, annual performance plan, or other guidance. (Recommendation 2) |
When we confirm what actions the agency has taken in response to this recommendation, we will provide updated information.
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| Department of Justice | The Attorney General of the United States should ensure that the Director of ATF develops performance measures for ATF's Operation Southbound and uses them to monitor the operation's effectiveness in combating firearms trafficking to Mexico. (Recommendation 3) |
When we confirm what actions the agency has taken in response to this recommendation, we will provide updated information.
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| Department of State | The Secretary of State should ensure that the Assistant Secretary of INL develops and uses baselines and targets and collects results for all INL performance measures to monitor its funding of the ATF FTIU and Mexican law enforcement capacity-building projects to combat firearms trafficking to Mexico. (Recommendation 4) |
When we confirm what actions the agency has taken in response to this recommendation, we will provide updated information.
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