斯蒂芬·米勒入主白宫将考验墨西哥的红线Stephen Miller’s White House will test Mexico’s red lines

On Friday, President Trump named Stephen Miller, the architect of his immigration agenda, as White House chief of staff, replacing Susie Wiles three days after Democrats won both chambers of Congress. As many of us who have watched him evolve since the first Trump administration, this appointment matters more for Mexico than the midterm results.

Although Miller’s fixation on immigration has fallen out of favor with voters, that will not stop him from coercing Mexico on security, with more open threats of direct U.S. military action. Mexico’s security chief, Omar Garcia Harfuch, should already be preparing for a White House that acts alone, possibly in opposition to Congress.

Miller has not been shy about how he sees the problem. At the Pentagon’s counter-cartel conference in Miami this past March, he called the cartels “the ISIS and al Qaeda of this hemisphere” and said they should be met with hard power and lethal force rather than criminal justice.

That describes a policy already in place: eight Mexican criminal groups designated foreign terrorist organizations since February 2025, ongoing lethal strikes on suspected drug boatssince September 2025, and around 500 troops sent to the Texas border this fall after an alleged shooting. As deputy chief of staff, Miller helped shape these decisions. As chief of staff, he controls who reaches the president and what lands on his desk. The officials who counseled patience with Mexico, if any remain, now have fewer ways in.

A Democratic Congress and the Republicans losses of so many elected positions across border states will not change this. If anything, Miller will push the White House toward the tools it controls alone: terrorist designations, Treasury sanctions, indictments, troop deployments and covert actions.

Unless Congress stops him, Miller will encourage Trump to continue using the cudgel of tariffs to exact concessions from President Claudia Sheinbaum. All of these are exactly the tools that reach into Mexico and weaken her presidency.

For two years, Mexico has answered relentless pressure with results. President Sheinbaum has granted unimaginable concessions to avoid direct attack on Mexico’s sovereignty.

Under her administration, Mexico has extradited or transferred 133 cartel figures to the United States in 2025 and 37 more in January. In February, a raid built on U.S.-shared intelligence killed Nemesio Oseguera Cervantes, known as “El Mencho,” leader of the Jalisco New Generation Cartel. Up to now, President Claudia Sheinbaum has run a two-track strategy of sovereignty rhetoric in her morning press conferences but close cooperation in practice.

Nevertheless, that cooperation has bought Mexico time, not safety. Eduardo Guerrero, one of Mexico’s sharpest security analysts, has tracked this dynamic all year. In January, he called each batch of transferred prisoners an offering to Uncle Sam and predicted that the National Palace will end up yielding once again to Washington. He judged a ground invasion unlikely, but said rapid drone strikes on cartel or political targets are possible.

In July, he described Washington’s turn from a war on drugs to a war on cartels: State, Justice, Treasury, the FBI and Homeland Security now treat cartel finances, logistics, and political protectors as terrorist infrastructure. In other words, the legal and bureaucratic architecture for unilateral action already exists. This is the landscape Miller inherits, with no guardrails on how he will use it.

The targets are also changing. In April, U.S. prosecutors charged Sinaloa Governor Ruben Rocha Moya, a member of Sheinbaum’s Morena party, along with nine officials. Mexico refused to extradite them, despite their possible links to organized crime. The same month, two CIA officers died in a crash in Chihuahua after a joint operation the federal government says it never authorized. Mexico’s attorney general has since charged a former Chihuahua prosecutor with treason for allowing U.S. involvement in the operation.

Guerrero asks the right question: Why is cooperation with Washington indispensable when the federal government runs it, and treason when a state does? The answer, I think, is that Mexico City already expects Washington to go around its authority and is trying to close every side door.

That is why García Harfuch must plan for unilateral action rather than for another round of intelligence sharing. He knows better than most how Mexico’s security apparatus behaves under foreign pressure: His father led the Federal Security Directorate in the late 1970s. Planning means protocols for what Mexico does if a U.S. strike lands on its territory. It means a public line on sovereignty settled before a crisis and protecting the state officials that cooperate in good faith.

It also means telling Washington plainly what decapitation has produced. Felipe Calderón’s kingpin strategy from 2006-2012 splintered the cartels, multiplied the violence and expanded the reach of organized crime. The removal of Joaquín “El Chapo” Guzman and Ismael “El Mayo” Zambada set off a brutal war between factions of the Sinaloa Cartel that continues today. Targeting leaders satisfies Washington, but it has fueled a crisis of insecurity and weakened the rule of law.

Coercion from Washington has produced cooperation from Mexico. The cost of that cooperation has fallen on migrants, border communities and Mexico’s weakest institutions and most vulnerable populations. Under Miller, that cost will grow.

Gladys McCormick is the Jay and Debe Moskowitz Endowed Chair in Mexico-U.S. relations at the Maxwell School of Citizenship and Public Affairs at Syracuse University. She has previously served as a senior associate at the Center for International and Strategic Studies in Washington.