For roughly 15 years, successive U.S. and Mexican governments have pursued close bilateral security cooperation. U.S. officials assess that Mexico-based drug cartels continue to pose a national security threat to the United States. Mexican drug cartels, six of which were designated as foreign terrorist organizations (FTOs) by the State Department in February 2025, have battled for control of illicit markets in Mexico and dominate the U.S. drug market. Mexico is the primary source of methamphetamine and fentanyl seized in the United States. These trends have continued despite efforts under the Mérida Initiative, which began in 2008, and its successor, the Bicentennial Framework (launched in 2021), for which Congress appropriated more than $3.6 billion (FY2008-FY2023).
The 119th Congress may evaluate lessons learned from past U.S.-Mexican security cooperation initiatives to inform funding, oversight, and potential conditions on U.S. security policies toward Mexico. Oversight may focus on the Trump Administration's efforts to counter the cartels and their implications for U.S. relations with Mexico.
Prior to FY2008, Mexico did not receive large amounts of U.S. security assistance, partially due to Mexican sensitivity about U.S. involvement in the country's internal affairs. In March 2007, then-Mexican President Felipe Calderón asked for more U.S. support to fight drug cartels. In response, the Mérida Initiative, a package of U.S. antidrug and rule-of-law assistance to Mexico, began. As part of the Mérida Initiative's focus on shared responsibility, the Mexican government pledged to tackle corruption. The U.S. government pledged to address drug demand and the illicit trafficking of firearms and bulk currency to Mexico. Both governments struggled to fulfill those commitments.
From FY2008 to FY2010, Congress appropriated $1.5 billion, including $420.7 million in Foreign Military Financing (FMF), which enabled the purchase of aircraft and helicopters to support Mexico's federal security forces. Congress required the State Department to withhold 15% of certain U.S. aid for the Mexican military and police until the agency submitted an annual report stating that Mexico was taking steps to meet human rights requirements. U.S. assistance focused on counternarcotics, border security, and counterterrorism; public security; and institution building.
In 2011, the U.S. and Mexican governments broadened the scope of bilateral efforts under four pillars: (1) combating transnational criminal organizations (TCOs); (2) strengthening criminal justice sector institutions while protecting human rights; (3) creating a 21st-century U.S.-Mexican border, while improving immigration enforcement in Mexico; and (4) building resilient communities through pilot projects aimed at violence prevention and reducing drug demand. Observers initially praised the initiative's breadth but later concluded the governments adopted new priorities without allocating adequate funding for them.
U.S.-Mexico security cooperation decreased after President Andrés Manuel López Obrador took office in December 2018. López Obrador gradually reduced federal security cooperation with the United States, with the exception of migration enforcement (a key priority of the Trump and Biden Administrations). In 2019, the López Obrador administration disbanded the federal police, which had received U.S. equipment and training but had engaged in corruption. The government created a National Guard drawn mostly from the military but under civilian authority.
Security cooperation further declined following the 2020 U.S. arrest of a former Mexican defense minister on drug charges based on investigations by the U.S. Drug Enforcement Administration. In response, Mexico's Congress enacted a law limiting foreign law enforcement activities in the country. The Mexican government stopped approving most Mérida Initiative programs. Nevertheless, intelligence sharing and cooperation continued in some states and municipalities, including in Mexico City, where President Claudia Sheinbaum then served as head of government (2018-2023).
In October 2021, U.S. and Mexican officials announced a new Bicentennial Framework for Security, Public Health, and Safe Communities with three pillars:
The framework envisioned a coordinated, "whole of government" approach to combating shared security challenges, but some analysts viewed the framework largely as reordering the Mérida Initiative's pillars and questioned whether it could resolve tensions that had erupted. In March 2023, U.S. and Mexican officials announced their intention to focus on combatting fentanyl production, arms trafficking, and TCOs. In October 2023, officials highlighted increased interdictions, arrests, indictments, and sanctions for arms and fentanyl trafficking as evidence of success. A September 2023 Government Accountability Office (GAO) report questioned how the framework's overall efficacy would be evaluated. Human rights groups criticized the framework for not adequately addressing impunity for human rights abuses by security forces. They urged U.S. officials to push for transparency and human rights safeguards as Mexico increased its use of the military in public security. In 2024, Mexico enacted a constitutional reform to put the National Guard permanently under the authority of the defense ministry.
The second Trump Administration has called for the "total elimination" of drug cartels, declared a national emergency on the southern border related to drug trafficking and unauthorized migration, and imposed a 25% tariff to incentivize Mexico to take more action on these issues. The designation of Mexican cartels as FTOs in February 2025 enabled the U.S. Department of the Treasury to impose counterterrorism sanctions on drug traffickers and their enablers. The Justice Department also has indicted Sinaloa and Jalisco New Generation Cartel members for providing "material support" of terrorism. The Trump Administration has expanded the U.S. military presence at the southern border and reportedly has issued a directive that would enable U.S. military actions against drug cartels designated as terrorist groups, including in Mexico.
President Sheinbaum has shown a willingness to collaborate with U.S. efforts to combat cartels, but continued tariff threats or U.S. military action in Mexico could damage cooperation. The Sheinbaum administration has deployed 10,000 Mexican National Guard troops to the country's borders to deter drug flows, transferred 55 high-level drug traffickers into U.S. custody, and allowed expanded U.S. surveillance flights over Mexican territory. In February 2025, U.S. and Mexican officials pledged to "secure our borders, dismantle cartel[s] ... and stop the illicit flows of drugs and weapons." As high-level officials met to discuss a bilateral agreement in July, President Trump threatened to raise tariffs on Mexico to 30% due, in part, to what he said were Mexico's insufficient efforts against drug cartels. He later postponed imposition of these tariffs for 90 days. The State Department reportedly has revoked some Mexican politicians' visas for reported criminal ties, including leaders in Sheinbaum's party. Despite tension in relations, Mexican authorities have been acting on U.S. intelligence to detain cartel leaders. The Sheinbaum government has rejected any unilateral U.S. military actions against cartels in Mexico.
The future role of U.S. foreign assistance in supporting U.S.-Mexico counternarcotics and rule-of-law efforts is in flux. Most security assistance to Mexico has been appropriated through the International Narcotics Control and Law Enforcement (INCLE) and, to a lesser extent, Economic Support Fund (ESF) accounts. INCLE assistance to Mexico averaged $100 million from FY2015 through FY2021 before falling to $64 million in FY2022 and $48 million in FY2023 (the last year publicly available). ESF accounts managed by the U.S. Agency for International Development (USAID) for human rights, crime prevention, and rule-of-law programs totaled $37 million in FY2023. The Trump Administration paused, reviewed, and ultimately canceled many U.S. foreign assistance programs and has sought to dissolve USAID. It is unclear what INCLE programs have continued.
Congress could influence bilateral security cooperation through appropriations, withholding requirements or restrictions on foreign assistance, other legislation, and oversight of the Trump Administration's approach to bilateral security cooperation.
The FY2024 Consolidated Appropriations Act (P.L. 118-47) did not specify a total appropriations level for Mexico. The act directed not less than $125.0 million in global ESF and INCLE funds to be allocated for programs to counter the flow of U.S.-bound fentanyl and other synthetic drugs, including in Mexico. The act also required the State Department to withhold 15% of any security assistance (including INCLE) made available for Mexico until the Secretary of State certified that the Mexican government had taken certain actions. Prior to obligating any INCLE assistance for Mexico, S.Rept. 118-71 required the Secretary of State to submit a report to the Appropriations committees on the Mexican government's efforts to address a number of human rights issues. Other requirements included the provision of separate reports to relevant committees on (1) how U.S. assistance to Mexico has supported efforts against synthetic drugs; (2) the outcomes of the Bicentennial Framework; (3) the status of U.S.-Mexico border security, and (4) ports in Mexico that play a role in synthetic drug production or trafficking. The Full Year Continuing Appropriations and Extensions Act (P.L. 119-4) provided funding at the same level and subject to the conditions in P.L. 118-47.
The Trump Administration requested $125 million for the INCLE account globally in its FY2026 budget request, less than 10% of the FY2025 funding level. Although Mexico is not specifically mentioned, the budget request specifies that those funds would be used to support programs that combat illicit synthetic drug trafficking.
The House Appropriations Committee's reported version of the FY2026 National Security, Department of State, and Related Programs Appropriations measure (H.R. 4779), which would provide nearly $1.9 billion for the INCLE account, does not designate a specific amount of assistance to Mexico. The bill would withhold 30% of any INCLE funding made available for assistance to Mexico until the Secretary of State certifies that Mexico has taken steps to lower the amount of fentanyl reaching the United States, counter TCOs, and support intelligence sharing and joint anti-drug operations, among other conditions. H.Rept. 119-217 recommends that assistance to Mexico focus on helping the government secure its borders, combat opioid and other drug trafficking, and strengthen judicial and security institutions. H.Rept. 119-217 would require the Secretary of State to report within 120 days of the bill's enactment on "Mexico's level of cooperation [in combating fentanyl]." See also CRS In Focus IF10400, Illicit Fentanyl and Mexico's Role.