Evolution of U.S.-Mexico Security Cooperation

Evolution of U.S.-Mexico Security Cooperation

Evolution of U.S.-Mexico Security Cooperation

Updated December 11, 2025 (IF10578)

For much of the past 15 years, successive U.S. and Mexican governments have pursued close bilateral security cooperation. Congress appropriated some $3.6 billion for such cooperation from FY2008 to FY2023. Nevertheless, U.S. officials assess that Mexico-based drug cartels, six of which the State Department designated as foreign terrorist organizations (FTOs) in February 2025, continue to pose a national security threat to the United States. Mexico is also the primary source of methamphetamine and fentanyl seized in the United States. Current Mexican President Claudia Sheinbaum (October 2024-present) has increased cooperation on counternarcotics efforts but has rejected any unilateral U.S. military actions in Mexico.

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 assistance for Mexico. Oversight may focus on the Trump Administration's efforts to counter the cartels and their implications for U.S. relations with Mexico.

The Mérida Initiative (2008-2021)

The Mérida Initiative, a package of U.S. antidrug and rule-of-law assistance to Mexico, began in 2008. As part of a focus on shared responsibility, the Mexican government pledged to tackle corruption. The U.S. government pledged to address drug demand, arms trafficking, and bulk cash smuggling to Mexico. Both governments struggled to fulfill those commitments. From FY2008 to FY2010, Congress appropriated $1.5 billion for the Mérida Initiative. U.S. funds focused largely on training and equipping Mexican security forces for counterdrug and border security efforts. From FY2008 through FY2015, Congress required the State Department to withhold a percentage of U.S. assistance to Mexican security forces until certain human rights conditions were met.

In 2011, bilateral efforts broadened to focus on four pillars: (1) disrupting organized criminal groups; (2) strengthening institutions; (3) creating a 21st-century U.S.-Mexican border; 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 that the governments adopted new priorities without allocating adequate funding for them.

Security cooperation decreased after President Andrés Manuel López Obrador took office in December 2018. López Obrador reduced federal security cooperation with the United States, with the exception of migration enforcement (a top U.S. priority). 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 after the 2020 U.S. arrest of a former Mexican defense minister on drug charges. Mexico's Congress enacted a law limiting foreign law enforcement activities in the country. The government also stopped approving most Mérida Initiative programs.

Bicentennial Framework (2021-2024)

In October 2021, U.S. and Mexican officials announced a new Bicentennial Framework with three pillars: (1) protecting people; (2) preventing transborder crime; and (3) pursuing criminal networks. The framework envisioned a coordinated, "whole of government" approach to combating shared security challenges. Some analysts viewed the framework as mostly a reordering of the Mérida Initiative's pillars; others said it deemphasized law enforcement cooperation. A September 2023 Government Accountability Office report questioned how the framework's overall efficacy would be evaluated. Human rights groups urged U.S. officials to push for more 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 under the authority of the defense ministry.

Current Security Cooperation

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 (Treasury) to impose counterterrorism sanctions on drug traffickers and their enablers. The Justice Department has indicted Sinaloa and Jalisco New Generation Cartel (CJNG) members for providing "material support" of terrorism. In June 2025, Treasury ordered the imposition of anti-money-laundering special measures on three Mexican financial institutions. After two delays, the orders took effect in October. The State Department reportedly has revoked some Mexican politicians' visas for reported criminal ties, including leaders in Sheinbaum's party.

President Sheinbaum has adopted a more aggressive security policy than her predecessor. The policy is led by security minister Omar García Harfuch. A close ally, Harfuch served in the same role during Sheinbaum's term as head of government of Mexico City (2018-2023). The Sheinbaum administration's strategy has focused on intelligence gathering, police investigations, and targeted interventions in high-crime states coordinated between federal and state authorities. Mexican officials report that the strategy has resulted in "high-impact" arrests; seizures of drugs, labs, and arms; and an overall decline in homicides of 32% (although violent crime remained elevated in some states).

The November 2025 public assassination of a mayor in Michoacán and apparent increase in enforced disappearances has prompted some criticism of the strategy. Critics maintain that deploying police and National Guard troops (as Sheinbaum has done to Michoacán) and arresting kingpins without combating corruption is likely to fail. Such deployments and a "kingpin" strategy arguably led to increased violence under the Felipe Calderón government (2006-2012). Efforts to address corruption and impunity could depend on the efforts of recently appointed prosecutor general Ernestina Godoy, who worked with Sheinbaum as Mexico City's prosecutor.

President Sheinbaum has shown a willingness to collaborate with U.S. efforts to combat cartels. 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 September 2025, the U.S. and Mexican governments issued a joint statement announcing a new high-level implementation group on security cooperation during Secretary of State Marco Rubio's visit to Mexico. Based on principles including "respect for sovereignty" and "shared and differentiated responsibility," the joint statement listed a broad variety of priorities, most of which were in prior bilateral initiatives. The joint statement did not identify clear goals or a means of assessing progress toward them. It does not appear to tie U.S. assistance to the strategy's execution. The first meeting of the implementation group focused on firearms trafficking—a top Mexican priority. Secretary of State Rubio has offered to provide training, equipment, and intelligence assistance to Mexico.

Ongoing bilateral cooperation could be derailed by any potential unilateral U.S. military actions in Mexico. The Trump Administration has expanded the U.S. military presence at the southern border. Since September 2025, the U.S. military has launched lethal strikes on vessels allegedly transporting illicit drugs for FTOs in international waters in the Eastern Pacific (near Mexico and Colombia) and in the Caribbean (near Venezuela). President Sheinbaum has opposed those strikes and rejected President Trump's statements asserting that he could launch unilateral U.S. military strikes against FTOs in Mexico.

The role of U.S. foreign assistance in supporting U.S.-Mexico security cooperation 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, the 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). It is unclear how the Trump Administration's terminations and changes in the management of foreign assistance have affected U.S. initiatives in Mexico.

Congressional Action

Congress could influence bilateral security cooperation through appropriations, withholding requirements, or restrictions on foreign assistance, among other legislation and oversight of the Trump Administration's approach.

The Department of State, Foreign Operations, and Related Programs Appropriations Act, 2024 (P.L. 118-47, Division F), carried through FY2025 and the first four months of FY2026 by P.L. 119-4 and P.L. 119-37, respectively, did not specify a total appropriations level for Mexico. The act (§7036) 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 (§7045(h)) also required the State Department to withhold 15% of any security assistance made available for Mexico until the Secretary of State certified that the Mexican government had taken certain actions to combat transnational crime.

S.Rept. 118-71, incorporated into the explanatory statement accompanying P.L. 118-47, 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 prior to obligating any INCLE assistance for Mexico. S.Rept. 118-71 also directed the State Department to provide 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 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 stated that those funds would be used to support programs that combat illicit synthetic drug trafficking. The National Security, Department of State, and Related Programs Appropriations Act, 2026 (H.R. 4779), reported by the House Appropriations Committee in July 2025, would provide nearly $1.9 billion in INCLE funding globally but would not designate specific assistance to Mexico. The bill (§7045(h)(2)) would withhold 30% of any INCLE funding for Mexico until the Secretary of State certifies that Mexico has met certain security-related conditions.

A House-Senate negotiated agreement for a National Defense Authorization Act for Fiscal Year 2026 (S. 1071) would require a report on joint training with Mexico to combat transnational criminal organizations (TCOs; §1274); a plan to improve counterdrug cooperation with Mexico (§6717); a report on addressing fentanyl trafficking from the People's Republic of China and countries such as Mexico (§8313); annual reports on efforts to prevent methamphetamine smuggling from Mexico (§8318); and a strategy for countering TCOs in Mexico that includes a review of the Mérida Initiative and Bicentennial Framework (§8365). The bill states that nothing in Section 8365 "may be construed as an authorization for the use of military force against Mexico or any entity within Mexico." See also CRS In Focus IF10400, Illicit Fentanyl and Mexico's Role.