One of the more surprising foreign policy ideas the Trump team has proposed on the eve of its ascension to power is military intervention in Mexico to go after drug cartels and possibly stop migrants headed to the United States.

The idea seemed so wild and provocative — siccing U.S. troops on a peaceful neighbor — that Mexican officials figured it was nothing more than Trump bluster aimed at revving up his base.

But now President-elect Donald Trump’s choice of Ronald D. Johnson to serve as ambassador to Mexico has them wondering if he is serious.

Johnson is both a former U.S. military officer — a Green Beret — and a former CIA official. And in his previous post as U.S. ambassador to El Salvador, Johnson was an enthusiastic enforcer of Trump’s policies in support of its president, Nayib Bukele, an authoritarian widely accused of human rights abuses in a massive crackdown on gangs and in silencing dissent.

Trump has already threatened Mexico with 25% tariffs on many of its exports to the U.S. — including tomatoes, avocados, tequila and car parts — if the government of President Claudia Sheinbaum does not “do more” to stop the entry of migrants and fentanyl into the U.S. over its southern border with Mexico.

Many economists say such an action would not only blow up prices for U.S. consumers but also probably send the Mexican economy into a free fall, which in turn could spur more migration to the United States.

“Mexico can expect enormous pressure,” Maureen Meyer, programs vice president at the Washington Office on Latin America, said in an interview. The focus will be almost exclusively on immigration and law enforcement, she predicted, while “issues of concern to the human rights community — reproductive rights, climate, democracy — will all take a step back.”

She and others said that will probably be true across Latin America as a Trump government fortifies common cause with right-wing governments and parties in Argentina, Brazil and elsewhere, but will have the most impact in Mexico because of its 2,000-mile border with the United States and its close economic and cultural ties.

Johnson, not to be confused with the Republican Wisconsin senator of the same name, has resided in Florida since stepping down as ambassador to El Salvador at the end of the first Trump administration. He is an Alabama native, married with four grown children and five grandchildren, and spent time in Iraq and Afghanistan as part of his CIA duties. He also worked on counter-insurgency operations during El Salvador’s civil war in the 1980s, when the U.S. supported the right-wing government against leftist guerrillas.

“Ron will work closely with our great Secretary of State Nominee, [Florida Sen.] Marco Rubio, to promote our Nation’s security and prosperity through strong America First Foreign Policies,” Trump said on Truth Social in announcing the nomination this month.

“Together, we will put an end to migrant crime, stop the illegal flow of Fentanyl and other dangerous drugs into our Country and MAKE AMERICA SAFE AGAIN!” Trump wrote. This week, Trump added a plan to designate Mexican drug cartels as terrorists, a step that might be used as authorization for deploying U.S. troops.

In his campaign platform, Trump said he would order the Pentagon to use “special forces, cyber warfare, and other covert and overt actions to inflict maximum damage on cartel leadership, infrastructure, and operations.”

But it remains unclear how many of these steps Trump could take unilaterally. Terrorist designations usually require action by other agencies, such as the State Department, and some members of Congress who advocate a tougher approach to Mexican drug trafficking are nevertheless reluctant to send U.S. troops into the fray without approval by the Mexican government.

In Mexico, news of Johnson’s nomination was greeted warily, with many seeing a clear signal of the Trump administration’s intended, narrow focus.

Johnson’s “resume is the message,” Jorge Castañeda, a former foreign minister in Mexico, said in an essay for the Nexos news website. “Johnson has no experience in economic, commercial or financial matters. He is not coming to Mexico for that.”

Where Johnson does have ample experience is in counter-insurgency.

Johnson probably “will demand a change in the security strategy in Mexico,” said Mexican commentator León Krauze. “Trump likes spectacle, and has long considered the possibility of delivering to his electorate images of unilateral incursions into Mexican territory to arrest major drug lords, Hollywood-style.”

Many in Mexico are weary of U.S. intervention in security matters and blame the U.S. in part for backing former President Felipe Calderon’s military assault on drug cartels beginning in 2006, which sparked devastating levels of violence that persist to this day. Still others, just as exhausted by high murder and kidnapping rates, and having lost confidence in Mexican law enforcement often bought off by criminals, have started to lean toward welcoming U.S. troops.

Security cooperation between the U.S. and Mexico diminished greatly during the presidency of Andrés Manuel López Obrador, who accused U.S. forces of “abusive meddling” in 2020 when the former Mexican defense secretary, Salvador Cienfuegos, was arrested at Los Angeles International Airport on suspicion of drug trafficking.

López Obrador forced the Trump administration to return Cienfuegos to Mexico, where he was awarded a major military decoration. The damage strained U.S.-Mexico relations and hampered work in Mexico by the U.S. Drug Enforcement Administration.

Sheinbaum, who took office Oct. 1, is similarly likely to be reticent in cooperating with Trump.

After his initial threats about military attack and tariffs, she telephoned him at his resort in Mar-a-Lago and then posted on X that Mexico would cooperate with the U.S. on relevant topics, but that the country would not bend to the will of the U.S. as it had in drug war that began in 2006.

“We are going to collaborate .. but without subordinating ourselves,” she wrote. “We will always defend Mexico as a free, sovereign and independent country.”

Eschewing the military-heavy approach of some of her predecessors could set Sheinbaum on a collision course with Trump and Johnson.

Sheinbaum “is not a Bukele type,” said Rep. Jim McGovern, a Massachusetts Democrat who specializes in Latin America and has been highly critical of the Salvadoran leader. “She wants good relations with Mexico … but is not looking to kiss Trump’s ring.”

Another major question is how Johnson would treat human rights issues in Mexico.

In El Salvador, where he was ambassador from 2019 to 2021, Johnson refrained from criticizing Bukele as the government rounded up tens of thousands of people in an effort to reduce gang crime. Some had gang affiliations, but many did not. According to human rights organizations, most were denied due process, innocents including children were detained, and hundreds were tortured in jail and died. Homicide rates declined substantially, although there is dispute over by how much.

Johnson also failed to sound the alarm over Bukele’s attempts to stack the country’s Congress and the Supreme Court with loyalists in what critics have described as a power grab that eroded El Salvador’s hard-fought democracy.

Bukele frequently spoke of his warm friendship with Johnson. The two were photographed yachting together in the Pacific off El Salvador’s coast. In June, long after Johnson had left his posting as ambassador, he joined Donald Trump Jr., Tucker Carlson and Rep. Matt Gaetz to attend Bukele’s inauguration to a questionably legal second term.

It is highly unlikely Johnson will have a similar relationship with Sheinbaum, Mexico’s first female president, a climate scientist by training, and representative of a leftist political party.

Wilkinson reported from Washington and Linthicum from Mexico City. A special correspondent in San Salvador also contributed.