June to October 2025 in Mexico City and Washington, D.C.   The U.S. Treasury's Financial Crimes Enforcement Network (FinCEN) punished three Mexican banks for allegedly laundering money for drug cartels, which has led to a massive diplomatic fight between the U.S. and Mexico.

  On June 26–27, 2025, Mexico's President Claudia Sheinbaum publicly accused Washington of taking financial moves on its own without showing proof.  She asked for written proof to back up what she said.

  President Claudia Sheinbaum remarked at a press conference on June 27, 2025, "We haven't gotten enough proof to back up these claims. Mexico respects due process and will only act on verified information."

  On June 25, FinCEN listed CIBanco, Intercam Banco, and Vector Casa de Bolsa as "primary money laundering concerns" under Section 311 of the USA PATRIOT Act. This is when the matter came up.  They did this because they were involved in cartel money transfers and payments for fentanyl precursors.

  The FinCEN Orders That Led to the Diplomatic Rift

  FinCEN noted that the three groups:

  Made it simpler for Chinese exporters to collect more than $2.1 million in cross-border payments for fentanyl precursor chemicals (2021–2024).

  Allowed the cartel to clean up $10 million in profits through fake businesses and a lot of accounts.

  Used U.S. correspondent accounts to disguise money transfers between the Gulf and Sinaloa cartels.

  The instructions, which are based on Section 311 and the FEND Off Fentanyl Act (2024), indicate that U.S. banks must stop giving money to the targeted banks by October 20, 2025.

  ([Sources: FinCEN.gov, Foley & Lardner LLP, Reuters, Treasury Press Release #SB0179])

  Mexico's official answer was, "Show us proof or give it back."

  President Sheinbaum's government has labelled the decision "unilateral and politically sensitive."   The National Banking and Securities Commission (CNBV) said it will look into the matter in Mexico, but it also said it would "only take action if verifiable evidence is provided."

  CNBV Commissioner Jorge Nuño said that Mexico's regulators were "blindsided" by the U.S. announcement and didn't find out about the penalties through diplomatic channels; they learnt about it through news reports instead.

  At the same time, Mexico's Foreign Ministry urged the U.S. Ambassador to come in for negotiations and demanded that the investigation materials that FinCEN used be made public.

  Foreign Secretary Alicia Bárcena said, "Mexico is not a satellite of U.S. enforcement."  She said that any sanction against Mexican institutions "must follow shared protocols and treaty frameworks."

  ([Sources: The Guardian, WSJ, CNBV Bulletin, and Mexico's Secretaría de Hacienda])