Mexico is the United States' largest trading partner, the source of most of the fentanyl that has killed several hundred thousand Americans, and the country through which most migrants reach the American border. Its criminal organisations control territory, elect mayors and are armed largely with weapons bought in American shops. The American president has declared them terrorist groups, put tariffs on Mexican goods, let the continental trade agreement lapse, and said more than once that American forces may act inside Mexico. Mexico's president, Claudia Sheinbaum, cooperates more than any predecessor and draws one line: no foreign troops.
Where it stands · September 2026
Mexican soldiers killed a suspected Los Reyes cartel leader in Michoacan on 1 September. Mexico pressed the United States on auto and steel tariffs in a meeting with Commerce Secretary Lutnick the next day. On 8 September the two countries began a joint anti-drone operation, High Eagle, at the border. Mexico arrested a Sinaloa Cartel suspect and issued a warrant in the killing of a Spanish student on 17 September. American officials said on 23 September they want Mexico free of cartels. Trade and security tensions rose on multiple fronts on 24 September.
What the dispute is about
Who fights the cartels, and where. Washington wants its forces and agencies free to strike in Mexico and says Mexico's state is too penetrated to do it. Mexico says intelligence and extraditions yes, soldiers and drones that kill, no.
Who is responsible. American demand and American guns, says Mexico. Mexican corruption and Chinese chemicals, says Washington.
Trade as the lever. Four fifths of Mexico's exports go north. Every security demand arrives with a tariff attached, and the trade agreement that protected Mexico expired as a treaty in July and now lives from year to year.
