Mexico is already reeling from violence involving criminal gangs that resembles some of the world’s worst wars. During the U.S. election campaign, Donald Trump – now the president-elect – promised to slap high tariffs on the United States’ southern neighbour, send back millions of migrants, and even bomb cartels.
Since 2006, when then-Mexican President Felipe Calderón declared war on drug cartels, perhaps half a million Mexicans have been killed and another 100,000 people disappeared in violence that followed. The government killed kingpins and dismantled big criminal organisations but set off conflicts among smaller groups, heavily armed mostly with weapons imported from the United States.
These groups profit from producing and transiting drugs to feed demand from the north. Fentanyl, a synthetic opiate that is estimated to have killed more than 80,000 people in the United States in both 2022 and 2023, has replaced cocaine and methamphetamine as the primary drug for export. The tentacles of these gangs also extend into extortion, other forms of crime, and even legal activities.
Successive leaders have failed to curb the bloodshed. Former Mexican President Andrés Manuel López Obrador left office in 2024 with high approval ratings, defying the anti-incumbent sentiment sweeping the world. But he made few inroads against gangs, despite putting more soldiers on the streets than ever before.
Mexico’s murder rates are still among the world’s highest. Homicide rates have dipped slightly in the past two years, though this is largely due to informal deals involving local authorities that have left criminals entrenched and profiting.
López Obrador’s successor and protégé – Claudia Sheinbaum, who won election in June – now has to contend not only with drug violence, but also with a Trump team that has Mexico in its crosshairs.
Rep. Mike Waltz, Trump’s pick to become the next national security advisor, co-sponsored legislation last year asking for authorisation to use force against cartels. That sounds far-fetched, but clamour for unilateral military action – whether through airstrikes on fentanyl labs or special forces operations to kill leaders – is growing among U.S. Republicans.
Trump may try to send back millions of Mexicans if his promised mass deportation of undocumented migrants begins. In late November, he threatened high tariffs on Mexican goods unless the flow of migrants and fentanyl stops – in effect tying other demands to trade policy, which – given the importance of exports to Mexico’s flagging economy – is likely to be Sheinbaum’s priority.
Sheinbaum has assured Mexicans that relations will survive. After all, López Obrador came to power defending the Latin American migrants who Trump denigrated, but the two presidents ended up getting along just fine. Mexico cracked down on migration and agreed to accept foreign migrants who had illegally entered and applied for asylum in the United States until their cases were resolved. Trump inked a new trade deal, due for revision in 2026, and despite the odd threat to strike drug traffickers, let the matter rest.
Sheinbaum has countered Trump’s threats, suggesting that – absent Mexico’s cooperation – migrant caravans heading to the north would resume. She has asked Washington to deport migrants to their countries of origin, not Mexico. She, too, may hope that reinforcing Mexico’s role as a migrant buffer or tighter counternarcotics coordination will placate Trump.
Without cooperation, expect a bumpy ride. Mass deportations, especially if they happen suddenly, could trigger upheaval in parts of Mexico as poorer states struggle to assimilate returns. Unilateral military action against cartels would almost certainly backfire. Taking out more gang leaders would set off more turf wars and fragmentation, while doing nothing to curb drug production. Fentanyl labs are low-tech and easily rebuilt.
Mexico would retaliate, perhaps with moves against U.S. economic interests. Tanking relations between two countries interconnected by trade, investment and family ties would spell disaster for both.