The first 13 recipients of the Pentagon’s new Mexican Border Defense Medal squeezed into the Oval Office last week, standing at attention around the Resolute Desk. The awards, issued to soldiers and Marines assisting President Donald Trump’s border crackdown, were replicas of military medals given out more than 100 years ago, when American warships shelled the port of Veracruz and General John J. Pershing led U.S. troops into Chihuahua. That was the last time the United States attacked its southern neighbor. The new medals, Trump told the troops, were “a big deal.”

Fentanyl’s record of mass destruction is not in doubt. U.S. health data show that the drug caused about 400,000 fatal overdoses during the past decade, the deadliest mass-addiction crisis in U.S. history. But in calling fentanyl a “weapon,” Trump appeared to further endorse the once-fringe view that Mexico’s drug cartels are not profit-seeking Mafias but terrorist organizations, analogous to groups such as the Islamic State and al-Qaeda, and therefore worthy of a military response. “There’s no doubt that America’s adversaries are trafficking fentanyl into the United States in part because they want to kill Americans,” Trump declared. “If this were a war, that would be one of the worst wars.” He has threatened air strikes on cartel sites inside Mexico, labeling its traffickers foreign terrorist organizations.

Trump’s invocation of war and his revival of a medal from a long-buried era of American military intervention in Mexico leave Mexican President Claudia Sheinbaum in a bind. She has to appease Trump enough to avoid air strikes while firmly standing up for Mexican sovereignty and maintaining her own domestic political support. Now in the second year of her six-year term, she has won widespread praise at home for her coolheaded handling of Trump so far: She has kept trade flowing and tariffs manageable while defusing calls for air strikes on Mexico from MAGA elements who view the country as more of an enemy than an ally. Whether Sheinbaum can hold that balance under increased pressure from the White House will be her key challenge for 2026.

I traveled to Mexico City this month and spoke with members of Sheinbaum’s administration, who view the coming year with trepidation. Mexico is preparing to co-host the FIFA World Cup with the United States and Canada at the same time that the three countries are conducting a formal review of the United States–Mexico–Canada trade agreement, reached seven years ago after Trump ripped up its predecessor, NAFTA. Security coordination for the tournament has put more attention on Mexico’s crime problems amid the trade negotiations.

“We have a president on the Mexican side who is more interested, much more interested, in cooperating than her predecessor was,” Roberta Jacobson, the former U.S. ambassador to Mexico, told me, referring to former President Andrés Manuel López Obrador. “I think she has done an amazing job navigating that minefield.” But treating fentanyl as a terror weapon and traffickers as terrorists converts what has been mostly a public-health and law-enforcement issue into a national-security threat, opening the door to a broader U.S.-military response.

Sheinbaum has drawn a red line at U.S. strikes on Mexican soil and said flatly last month that they “would not happen.” Her government has set other firm limits on what it considers to be nonnegotiable matters, rejecting the possibility of joint operations that would allow armed U.S. forces to embed with Mexican troops, as the United States has done in Colombia and other drug-war theaters. U.S. and Mexican officials I spoke with told me that Sheinbaum has been willing to expand cooperation on almost everything else.

U.S. and Mexican diplomats spent years developing an approach to bilateral relations that sought to compartmentalize traditional sources of tension—trade, migration, water rights, drugs—so that they would not affect other areas. But Trump ditched that framework during his first term, when he threatened to crash the Mexican economy with crippling tariffs as a way to force Mexico to crack down on Central American migrants headed north.

[Read: Fentanyl doesn’t come through the Caribbean]

Mexican officials suspect that Trump’s talk of terrorism and WMDs is a way to gain leverage in the upcoming trade negotiations. Migration and security are at the top of Trump’s agenda, one adviser to Sheinbaum told me, “but the economic issue is always what’s really behind it.”

In the trade talks, the United States is seeking to further limit Chinese investment and influence in Mexico, to broaden liberalization of Mexico’s energy sector, and to advance a range of other manufacturing-, labor-, and farming-related goals. Mexico surpassed China in 2023 to become the top exporter to the United States, a result of the nearshoring boom led by U.S. manufacturers moving operations out of China. More than 80 percent of Mexico’s exports—cars, appliances, fresh produce—now go to the United States, leaving Mexico more dependent than ever on its northern neighbor, and subject to Trump’s whims.

Trump threatened Sheinbaum with more tariffs again this month to force Mexico to send more water from its reservoirs to farmers and ranchers in Texas. Sheinbaum moved quickly to appease him. “He’s not someone you can confront head-on, because he responds with more force,” the adviser told me. Sheibnaum, he said, “has been very clear about Mexico’s position without getting into a conflict.”

The adviser added, “This next year is going to be challenging for Mexico.”

Raúl Benítez Manaut, an expert on U.S.-Mexico security cooperation at the National Autonomous University of Mexico, told me that the CIA, the U.S. military, Homeland Security Investigations, the FBI, and other American agencies have been operating in Mexico with far more latitude than Mexican authorities would like to publicly acknowledge. Polling shows that many Mexicans, especially in the business community, would welcome a more muscular American role in their country, but this remains especially taboo for some members of Sheinbaum’s leftist Morena party. “She has to say certain things, for political necessity, to keep her base happy,” Benítez Manaut said. “Not unlike Trump.”

Benítez Manaut said that there would be major risks to air strikes—with or without Mexico’s consent—targeting illegal fentanyl production. The cartels have been moving their labs into cities because rural sites can be detected more easily by satellites, sensors, and other tools, he said. They believe that the government would be too worried about collateral damage to carry out a strike in an urban area. And any U.S. operation on Mexican soil would have to be very careful to “avoid hitting civilians,” Benítez Manaut said: “If someone innocent dies—a child, or a cleaning lady—it would be a shitstorm.”

On December 6, a pickup truck packed with explosives blew up outside the police station in Coahuayana, a small town in the state of Michoacán, one of the country’s bloodiest cartel battlegrounds. The blast shredded vehicles, knocked down trees, and killed six people, including three officers. Video footage of the site showed a charred blast radius strewn with debris that stretched for a block.

In Mexico, the bomb revived fears that drug-trafficking groups, if squeezed too hard, could begin to act like terrorist organizations in retaliation against the Mexican government. A bombing attack outside a World Cup venue would devastate Mexico and Sheinbaum’s government. The senior Mexican officials I spoke with told me that they are eagerly cooperating with the United States to share intelligence to avoid disaster.

Mexico’s drug smugglers are under pressure. Trump claims that there has been a huge slowdown in drug trafficking at sea since the U.S. began striking alleged smuggling vessels in the Caribbean and the eastern Pacific. The cartels are already contending with the loss of revenue from human smuggling and extortion payments along the U.S.-Mexico border as a result of Trump’s border crackdown. In October, handwritten cartel banners known as narcomantas appeared in the tourist resorts of Baja California threatening to kill Americans—signs that suggested a degree of desperation. Fentanyl, which is smuggled mostly by human couriers and vehicles through official crossings along the U.S. border, remains a major profit source for the cartels.

Trump is the first U.S. president to treat drugs as mass-casualty weapons and cartels as terror groups, applying the tools of America’s response to the 9/11 terror attacks to the vexing addiction crisis of the past decade. In an effort to draw more attention to soaring drug-overdose rates, public-health advocates calculated that more Americans were dying from opioids than from foreign wars or terror attacks. But the U.S. government had never before used these rhetorical comparisons to create justifications for military attacks.

[Read: Trump discovers Maduro’s Achilles’ heel]

Trump has said at least 17 times since September that “land strikes” against drug-production sites and other targets will commence “soon,” according to a recent CNN tally. The strikes so far have hit targets at sea near Venezuela. But Trump has said that action will not be limited to Venezuela. “We’re going to start hitting them on land, which is a lot easier to do,” the president said during the Oval Office ceremony, calling traffickers “a direct military threat to the United States of America” who are “trying to drug-out our country” in similar fashion to the way China’s imperial power was undermined by British-backed opium traders in the 19th century.

Mexico’s security cooperation with the United States fell to a low point under López Obrador, who lashed out at the Drug Enforcement Administration after U.S. agents arrested a Mexican general and former defense minister at Los Angeles International Airport and accused him of working with traffickers. López Obrador’s denunciations tapped into long-standing resentments toward the DEA as a meddlesome presence that wiretapped whomever it wanted, cut deals with cartel bosses, and interfered in Mexican politics. He ordered Mexico’s military to shun the agency.

A senior Mexican official and a senior U.S. official told me separately that cooperation has improved dramatically under Sheinbaum and that U.S. agencies, even the DEA, have regained space. Secretary of State Marco Rubio told reporters in September that “it is the closest security cooperation we have ever had.” Mexico has extradited more than 50 cartel suspects to the United States since February, including Rafael Caro Quintero, one of the DEA’s most wanted men. Mexican authorities have worked with the U.S. to seize more of the chemicals used to make fentanyl and other synthetic drugs and to go after the companies, mostly in China, that ship them.

The senior official in Sheinbaum’s government told me that “the reality is that there’s a lot of cooperation” and that the Trump administration has “been respectful so far about our red lines.”

Sheinbaum and her aides have learned to deal with Trump by separating his political statements and social-media posts from the practical, material matters of what the United States actually wants.

“I don’t think they will change their rhetoric, but as long as the actual relationship is good and works between the boundaries on what is acceptable for the two countries, we’re fine,” the senior Mexican official told me.

The CIA and the U.S. military are working with Mexico’s military, especially its elite marine-commando units, as the United States has done for years, passing along intelligence from informants and wiretaps on the whereabouts of cartel bosses and drug shipments. U.S. drones and surveillance aircraft circle Mexico’s skies, hunting drug labs. “The basis of that cooperation is: The U.S. can give us intelligence, but the security forces operating in Mexican territory need to be Mexican forces,” the senior Mexican official said. Officials at the U.S. embassy in Mexico City declined my interview request.

Mexico faces “constant pressure” from Trump officials, the senior Mexican official said: “I don’t expect that to change, to be honest. But I do believe that we have found common ground, and I do believe that a lot of people in Washington understand the nuances, the sensitivities, the complexities of the bilateral relation. And they know that doing some sort of strike within Mexican territory, either in the sea, the land, the air, whatever, would cross a line that it would be very difficult to recover from.”

Mexico’s navy invited me to visit its command-and-control center in Mexico City, where officials coordinate interdictions with the U.S. Coast Guard and other agencies. The center’s commander, Rear Admiral Máximo Rodríguez Villalobos, told me that cooperation between the two countries is “as strong as ever.” Rodríguez Villalobos said that the U.S. Coast Guard asked Mexico to respond to the site in international waters, off Mexico’s Pacific Coast, where the U.S. had attacked a suspected drug boat. “We reached the site, but we found no one,” Rodríguez Villalobos said. “There was nothing left.”

In the 1990s, U.S. forces intervened in Colombia, helping its government battle Marxist insurgents and take down drug lords such as Pablo Escobar. I asked the rear admiral if he could envision Mexico embracing a similar approach to Colombia’s as a way to avoid U.S. unilateral action, with U.S. agents and troops carrying out joint operations alongside Mexico’s security forces. “To arrive at the point Colombia reached at that moment, I don’t see it,” he said.

Today, Colombia is producing near-record amounts of cocaine, primarily for the U.S. market. The United States maintains security agreements with Colombia, but in October, the Trump administration decertified the country as a reliable drug-war partner for the first time in nearly 30 years. Trump is now threatening to carry out strikes on suspected drug labs in Colombian territory and trading insults with the leftist President Gustavo Petro.

U.S.-Mexico security cooperation reached a high point in the years after the 2008 Mérida Initiative, when then–Mexican President Felipe Calderón declared war on the country’s criminal groups. U.S.-trained Mexican marines worked with the CIA and the DEA to target cartel leaders in daring operations using U.S.-supplied Black Hawk helicopters. The United States spent hundreds of millions of dollars to help reform the Mexican judicial system as part of an effort to prosecute suspected traffickers instead of killing them.

Back then, U.S. officials were the ones encouraging Mexico to gather evidence and build prosecution cases. The work was difficult and often frustrating to both nations, especially when cases were mishandled and cartel suspects went free. Now it’s the U.S. government, under Trump, that appears to favor lethal force over prosecution and building institutions that could stand up to the cartels’ influence. I asked the rear admiral if Mexico endorsed that approach and if he thought it would be effective.

He considered his words carefully. “Every country has the right to pursue its objectives as it sees fit,” he said.

At the western end of the Paseo de la Reforma, Mexico City’s stately central artery, the Altar a la Patria, one of the country’s most important civic shrines, rises above the tree line of Chapultepec Park. The memorial consists of six white marble columns arranged in a semicircle honoring the Niños Héroes (the “Boy Heroes”)—young cadets killed in 1847 after they refused to surrender to invading American troops. On a recent Sunday morning, bike riders and tourists posed for snapshots under the looming monument while a man on roller skates looped through the crowd, bopping to Shakira songs on his portable speaker.

Mexico’s national identity is deeply entwined with this legacy of U.S. conquest and imperial bullying. The United States took half of Mexico’s land in the mid-19th century and periodically intervened in the decades that followed to protect American interests. During the past century of mostly good relations, U.S. politicians learned to work with Mexico by navigating this history with tact and respect.

Arturo Sarukhán, who served as Mexico’s ambassador to the United States under Calderón and who still lives in Washington, told me that those urging Trump to strike Mexico “really want to send a message” by taking a hammer to those sensitivities. Even a single missile strike on a fentanyl lab could undo a century’s worth of diplomacy.

[Read: Trump’s boat strikes could make the cartel problem worse]

Sheinbaum should redouble efforts to prevent such a scenario, Sarukhán said, first by saying definitively that Mexico’s cartels—not U.S. imperialism—are the greatest threat to her country’s sovereignty. Such a declaration could relaunch security collaboration with the United States along the lines of the Mérida Initiative, he said, including a “boots on the ground” U.S. presence working hand in hand with Mexican forces “under the control of Mexico but in dual coordination with United States authorities.”

“That would be closer to the Colombia model they say they don’t want to accept,” Sarukhán said. “But if you really want to defuse the unilateral use of force, the declaration of organized-crime organizations as foreign terrorist organizations, and now fentanyl as a weapon of mass destruction, I don’t see any other way of defanging those in the White House who are itching to drop a missile from a drone onto a lab in Sinaloa.”

The World Cup, Sarukhán said, provides an opportunity for Sheinbaum to manage potential political blowback, especially from her own party, because “what you can do is sort of underscore that you’re strengthening border security between Mexico, Canada, and the United States” to protect the games.

That approach, with its emphasis on the regional security of North America, would get the countries back to the framework that has aided decades of economic integration—and to a relationship that most flourishes when it’s not too fixated on the past.