As president, Donald Trump showed contempt for America’s bipartisan war party. Nevertheless, he was still tempted by military power, for instance suggesting that the U.S. target Mexican drug labs with missiles. In January candidate Trump proposed deploying “all necessary military assets, including the U.S. Navy,” designating “the major cartels as Foreign Terrorist Organizations,” and making “appropriate use of special forces, cyber warfare and other overt and covert actions to inflict maximum damage on cartel leadership, infrastructure and operations.”

Indeed, several members of his incoming administration, including Vice President-elect J.D. Vance, the incoming National Security Advisor Mike Waltz, currently a congressman for Florida, and Tom Homan, set to become “border czar,” also have proposed that Washington invade Mexico. A gaggle of other conservatives and Republicans, including most of Trump’s primary opponents, have made similar arguments.

Most of the proposals are tough in tone but spare on details. Last year Trump’s acting deputy secretary of the Department of Homeland Security, Ken Cuccinelli, proposed conducting “specific military operations to destroy the cartels” with special operations forces and airpower, and, if necessary, “elements of the Marines, Army, Navy, Air Force and Coast Guard.” He termed this “waging defensive war” and “defending the United States.” Everyone sounds certain of success. The Fox News host Greg Gutfeld contended: “It’ll be over in minutes.”

Alas, reality suggests a very different result. The primary drug problem is in America, not Mexico. Drugs cross the border because Americans want to buy them. Most smuggling north involves Americans. The Mexican cartels are not creating demand for fentanyl (as well as cocaine and marijuana). Last year Andres Manuel Lopez Obrador, known as AMLO, snapped: “Unjustly, [Americans] are blaming us for problems that in large measure have to do with their loss of values, their welfare crisis.”

If dealers are waging war on anyone, it is on Mexicans. Sen. Tom Cotton (R‑AK) observed that “Mexico has now deployed over 200,000 federal troops to fight the cartels, which have forced our neighbor into a worsening civil war. Yet, even with this massive military presence, the death-squad massacres, kidnappings, and decapitations continue.” That is all occurring in Mexico. In the view of most Mexicans, their society is being ravaged because of America’s failings.

What would the U.S. military target? It would face neither a state nor armed forces, but shadow institutions submerged in the population. Criminal leaders undoubtedly would go underground. It would be difficult to locate small fentanyl labs, which lack the identifying characteristics of methanol production. Observed Nathan Jones of Sam Houston State University, “Fentanyl is a highly decentralized market, so at this point, we’ve seen so many actors enter the fentanyl market, it’s not like that there’s just two cartels we could target.” As long as Americans want the drugs, Mexicans will provide them.

This has been the problem with Washington’s other drug-based military campaigns. Noted Reason’s Fiona Harrigan: “The war on drugs has helped turn Latin America into the most violent region in the world. Criminalization has led to the proliferation of black market activity, a boom in many countries’ prison populations, and increased corruption across Latin America. It’s also contributed to a huge number of homicides.”

Earlier U.S. efforts, including in Mexico and Colombia, did little to cut drug production. Gil Barndollar of Defense Priorities wrote about his time in Afghanistan. His unit

engaged in erratic, futile attempts to interrupt opium-poppy cultivation. Partnered with Afghanistan’s version of the U.S. Drug Enforcement Agency, my company wasted days fruitlessly searching motorcycles at checkpoints on dusty village trails, finding no drugs. On one occasion, I was ordered to confiscate farmers’ wooden poppy scorers, simple finger-mounted tools used to harvest opium; at a cost of maybe a penny a piece, they were immediately replaced. U.S. planes bombed 200 Afghan drug labs during the occupation. Yet opium production skyrocketed—Afghanistan produced more than 80 percent of the global supply of the drug in the last years of the war.

Moreover, unlike these operations, invading Mexico would limit local assistance. Ironically, treating dealers as terrorists, as proposed by the president-elect and others, would misuse the law and limit American cooperation with Mexican citizens and groups tied, however indirectly, to the organizations. Moreover, in recent years the country has moved decidedly left and towards nationalism. AMLO, president from 2018 to 2024, was no fan of intrusive U.S. demands. Last March he declared: “We are not going to permit any foreign government to intervene in our territory, much less that a government’s armed forces intervene.” His protégé, Claudia Sheinbaum Pardo, took over on October 1. After her recent conversation with Trump she rejected his claim that she agreed to his demands on migration and trade. Equally unlikely is support by the Mexican military. Federico Estévez of Mexico’s Autonomous Technological Institute warned “The Mexican military will not accept gringo overlordship.”

Advocates of military action nevertheless imagine that Washington’s threats would compel Mexican assistance. However, history hangs heavily over the U.S.–Mexico relationship. In 1846 America’s land-grabbing President James Knox Polk seized half of Mexico. Decades of imperious U.S. treatment generated President Porfirio Díaz’s famous lament: “Poor Mexico—so far from God, and yet so close to the United States.” American military forces operating against Mexicans in Mexico could not help but offend. Former foreign minister Jorge Castañeda predicted: “Any Mexican president, whether it’s the current one or any of his recent predecessors, would react by terminating bilateral cooperation agreements.”

In the best case, the Mexican government would simply cease working with Washington, whether to interdict drugs, discourage migration, or achieve other American ends. Mexico City might boycott trade, disrupting U.S. supply chains, and likely would lead an international diplomatic offensive against the U.S. What then would Washington do? Occupy Mexican territory and displace the established authorities? Track down gang members and operations on its own? Overspread the country to confront a constantly mutating commercial network? Target criminal leaders, already folk heroes to some, turning them into symbols of resistance? Run the equivalent of a counterinsurgency, amid a hostile population and institutions? While many Mexicans would love to see the cartels crippled, others benefit from the operations, whose leaders and soldiers are members of the community with ties to politicians and security officials. These organizations also spread the wealth—for instance, hiring college chemistry students for fentanyl production.

And it could be much worse. Although the national government would not likely directly confront U.S. forces, there might be organized, if unofficial, resistance. Groups of police, soldiers, and others could attack roving American detachments. Indeed, the U.S. military estimates that upwards of a third of the country is essentially ungoverned today. Worries Antonio De Loera-Brust, formerly at the State Department and a congressional staffer: “In large parts of Mexico, local Mexican police and government forces can’t maintain order. It is unclear why this would lead anyone to expect the U.S. would be able to.” Mexicans mounted irregular resistance to Washington’s invading army in 1846 and a major U.S. incursion in 1916.

Nor should one underestimate the cartels. Today they generally avoid targeting Americans, which would risk triggering a U.S. response. In March one organization handed over five men blamed for abducting four Americans and killing two of them, explaining that the former “at all times acted under their own decision-making and lack of discipline.” However, if the U.S. attacks the gangs, they will have no reason to hold back. They possess significant military weapons. Many of their personnel have received military training, as members of the Mexican armed forces and beneficiaries of U.S. military programs, and perhaps even directly from former American personnel. They have at times overmatched police forces and even the army.

America’s formal military superiority would not guarantee an easy victory. Observed the Cato Institute’s Brandan Buck: “Man-portable weapons systems and armed UAVs favor those who hold territory, thereby leveling the scales between otherwise mismatched military forces.” And Washington would lack the local allies who did most of the fighting in Afghanistan, Iraq, Libya, Syria, and elsewhere. Russia and Iran could be expected to aid America’s opponents as obvious payback for Ukraine and more.

Perhaps worse, with roughly $2 trillion in commerce, 1.6 million Americans living in Mexico, and extensive personal ties between Mexicans and Americans, there would be ample soft targets for cartel retaliation. The conflict might wreck an already fragile Mexican state with potentially catastrophic consequences. The Global War on Terrorism caused extraordinary destruction, chaos, and death, from which the U.S. remained largely immune. In contrast, Mexico is next door. Barndollar observed: “Any unilateral U.S. military action in Mexico would risk the collapse of a neighboring country of 130 million people. It could unleash civil war and a humanitarian crisis that would dwarf those in Iraq and Syria. This carnage would not be confined to Mexico. Some of America’s largest and wealthiest cities are a few hours’ drive from the border.” Imagine a human tsunami racing toward the border.

In this endeavor the U.S. would be friendless internationally. There would be little regional support. America would be denounced by the Global South, which has disdained Western moralizing in Ukraine. Adversaries would highlight American hypocrisy and violence. Even the Europeans would find it difficult to back the U.S.

Finally, this abundant death and destruction might not much reduce the fentanyl supply. The Cato Institute’s Ted Galen Carpenter and Jeffrey A. Singer warned of the consequences of “the iron law of prohibition.” Enhanced enforcement raises prices, drawing in new producers and encouraging greater drug concentrations, which “is why fentanyl has replaced heroin as the primary cause of overdose deaths in the U.S. It is why dealers are now boosting fentanyl with the veterinary tranquilizer xylazine (“tranq”), and might be in the process of replacing fentanyl with the more powerful synthetic opioid isotonitazene (“iso”).”

War is no answer for the drug crisis. Even the otherwise sensible Cuccinelli engages in fantasy: “Waging war against the cartels and confronting select cartel networks and affiliate factions in a manner similar to existing [terrorist] designations is the surest way [emphasis added] to bring an end to the chaos.” Such a policy is far easier to pronounce with certainty than implement with success.

President Trump recognized the danger of overusing military force. The president-elect should have no illusions about the consequences of a war both within and against Mexico. He could end up wrecking not only America’s southern neighbor, but also his nascent presidency.