A second Trump administration was sure to come down hard on whichever Latin American country first defied it—few in the region expected otherwise. But Colombia was perhaps the United States’ most steadfast friend in South America, and the speed with which a 100-year relationship seemed to crumble last night was frightening.

Or perhaps exhilarating, if you were a Chinese diplomat in Latin America observing the presidential spat.

First, Colombia’s president, Gustavo Petro, refused to allow U.S.-military deportation flights that were already airborne to land in his country. Petro balked at reports of migrants arriving handcuffed and said that Colombia would allow such flights only if deportees were treated with “dignity and respect.” President Donald Trump’s response—grossly disproportionate—was to threaten tariffs, visa restrictions, and even banking sanctions against a strategic U.S. ally. The two countries worked out a late-night deal that seems to have averted a crisis, but the speed of escalation left much of Latin American unnerved.

[From the September 2024 issue: Seventy miles in hell]

If Americans are under the impression that Trump’s penchant for reckless, heat-of-the-moment policy making is unique, they don’t have the measure of Gustavo Petro. Colombia’s radical left-wing president has appalled friends and foes alike with X tiffs and stunts such as repeatedly tagging a parody account for his defense minister and amplifying false rumors that Colombian kids lost in the Amazon jungle had been found. Some of his posts come across as just plain bonkers—such as the one he wrote to Trump in the middle of yesterday’s crisis.

At 4:15 p.m. on Sunday, diplomats were working furiously behind the scenes to smooth over the rift between the two presidents when Petro hit back with a long, incoherent rant. Starting with a curt dismissal of tourism in the U.S. as “boring,” the missive went everywhere: Petro slammed American racism, asserted his refusal to “shake hands with white slavers,” and celebrated Walt Whitman. He also recalled the U.S. involvement in the 1973 coup against Chile’s leftist president Salvador Allende, celebrated Colombia’s putative roots in the caliphate of Córdoba, and protested the execution of Sacco and Vanzetti, a Coolidge-era U.S. scandal involving the supposed racial profiling of two Italian American anarchists. In other words, at a moment of peril for his country, Colombia’s president posted a word salad—and then pinned it to the top of his X account.

The moment called for careful diplomacy, not a fit of pique. In Brazil, where the mistreatment of deportees on U.S. military flights had already caused controversy, Colombia’s spat narrowed the Brazilian government’s room for maneuver still further. And throughout the region, governments struggling to figure out what to do with large numbers of deportees found themselves staring into the abyss: Most Latin American governments do not like how the U.S. government is behaving but cannot afford a trade war with Uncle Sam.

Or can they? Zoom out a bit and one might wonder. The era of uncontested U.S. leadership in the region is fading fast in the rearview mirror. These days, China provides an obvious alternative to the United States in the realms of trade, finance, and technology. In fact, most of South America—including big countries such as Brazil, Argentina, Chile, and Peru—now trades more with China than with the United States. If you exclude Mexico, Chinese trade now dwarfs American trade in the region.

[Juliette Kayyem: The border got quieter, so Trump had to act]

After Trump was reelected, discussion in the region centered on how to balance growing Chinese influence with existing ties with the United States. Most countries were of a mind to try to stay neutral between the two powers and maintain good relations with both Washington and Beijing. Countless university seminars agonized over what a war in the Taiwan Strait would mean for Latin America: No country in the region would want to take sides, though many recognized that they might not have a choice. All along, the assumption tended to be that a crisis that started outside Latin America would have repercussions within it. What few at the time foresaw was that the region could be delivered to China through Trump’s sheer impetuosity, or his inability to think before posting.

For now, Trumpian aggression has won the day: U.S. and Colombian diplomats—who know each other well and are used to collaborating closely—had little trouble finding a compromise to de-escalate the crisis. That de-escalation can be expected to last about as long as the two countries’ intemperate presidents manage to stay off X.

But for excellent historical reasons, Latin Americans hate being dictated to by gringos and won’t support leaders who meekly allow it. Trump’s hyper-aggressive approach to Latin America risks tying up the region with a bow and leaving it on Beijing’s doorstep. Most Latin American leaders will resist a decisive break with Washington—the U.S. is still too important a trade and diplomatic partner to antagonize just for kicks. But Latin American leaders will not wish to be seen submitting passively to the United States in full imperialist mode. Not when the Chinese embassy is just one phone call away.

In the world of nutrition, few words are more contentious than healthy. Experts and influencers alike are perpetually warring over whether fats are dangerous for the heart, whether carbs are good or bad for your waistline, and how much protein a person truly needs. But if identifying healthy food is not always straightforward, actually eating it is an even more monumental feat.

As a reporter covering food and nutrition, I know to limit my salt and sugar consumption. But I still struggle to do it. The short-term euphoria from snacking on Double Stuf Oreos is hard to forgo in favor of the long-term benefit of losing a few pounds. Surveys show that Americans want to eat healthier, but the fact that more than 70 percent of U.S. adults are overweight underscores just how many of us fail.

The challenge of improving the country’s diet was put on stark display late last month, when the FDA released its new guidelines for which foods can be labeled as healthy. The roughly 300-page rule—the government’s first update to its definition of healthy in three decades—lays out in granular detail what does and doesn’t count as healthy. The action could make it much easier to walk down a grocery-store aisle and pick products that are good for you based on the label alone: A cup of yogurt laced with lots of sugar can no longer be branded as “healthy.” Yet the FDA estimates that zero to 0.4 percent of people trying to follow the government’s dietary guidelines will use the new definition “to make meaningful, long-lasting food purchasing decisions.” In other words, virtually no one.

All of this is a bad omen for Donald Trump’s pick to lead the Department of Health and Human Services. As part of his agenda to “make America healthy again,” Robert F. Kennedy Jr. has pledged to improve the country’s eating habits by overthrowing a public-health establishment that he sees as ineffective. He has promised mass firings at the FDA, specifically calling out its food regulators. Indeed, for decades, the agency’s efforts to encourage better eating habits have largely focused on giving consumers more information about the foods they are eating. It hasn’t worked. If confirmed, Kennedy may face the same problem as many of his predecessors: It’s maddeningly hard to get Americans to eat healthier.

[Read: Everyone agrees Americans aren’t healthy]

Giving consumers more information about what they’re eating might seem like a no-brainer, but when these policies are tested in the real world, they often do not lead to healthier eating habits. Since 2018, chain restaurants have had to add calorie counts to their menus; however, researchers have consistently found that doing so doesn’t have a dramatic effect on what foods people eat. Even more stringent policies, such as a law in Chile that requires food companies to include warnings on unhealthy products, have had only a modest effect on improving a country’s health.

The estimate that up to 0.4 percent of people will change their habits as a consequence of the new guidelines was calculated based on previous academic research quantifying the impacts of food labeling, an FDA spokesperson told me. Still, in spite of the underwhelming prediction, the FDA doesn’t expect the new rule to be for naught. Even a tiny fraction of Americans adds up over time: The agency predicts that enough people will eat healthier to result in societal benefits worth $686 million over the next 20 years.

These modest effects underscore that health concerns aren’t the only priority consumers are weighing when they decide whether to purchase foods. “When people are making food choices,” Eric Finkelstein, a health economist at Duke University’s Global Health Institute, told me, “price and taste and convenience weigh much heavier than health.” When I asked experts about better ways to get Americans to eat healthier, some of them talked vaguely about targeting agribusiness and the subsidies it receives from the government, and others mentioned the idea of taxing unhealthy foods, such as soda. But nearly everyone I spoke with struggled to articulate anything close to a silver bullet for fixing America’s diet issues.

RFK Jr. seems to be caught in the same struggle. Most of his ideas for “making America healthy again” revolve around small subsets of foods that he believes, often without evidence, are causing America’s obesity problems. He has warned, for example, about the unproven risks of seed oils and has claimed that if certain food dyes were removed from the food supply, “we’d lose weight.” Kennedy has also called for cutting the subsidies doled out to corn farmers, who grow the crops that make the high-fructose corn syrup that’s laden in many unhealthy foods, and has advocated for getting processed foods out of school meals.

There’s a reason previous health secretaries haven’t opted for the kinds of dramatic measures that Kennedy is advocating for. Some of them would be entirely out of his control. As the head of the HHS, he couldn’t cut crop subsidies; Congress decides how much money goes to farmers. He also couldn’t ban ultra-processed foods in school lunches; that would fall to the secretary of agriculture. And although he could, hypothetically, work with the FDA to ban seed oils, it’s unlikely that he would be able to generate enough legitimate scientific evidence about their harms to prevail in an inevitable legal challenge.

The biggest flaw in Kennedy’s plan is the assumption that he can change people’s eating habits by telling them what is and isn’t healthy, and banning a select few controversial ingredients. Changing those habits will require the government to tackle the underlying reasons Americans are so awful at keeping up with healthy eating. Not everyone suffers from an inability to resist Double Stuf Oreos: A survey from the Cleveland Clinic found that 46 percent of Americans see the cost of healthy food as the biggest barrier to improving their diet, and 23 percent said they lack the time to cook healthy meals.

If Kennedy figures out how to actually get people like me to care enough about healthy eating to resist the indulgent foods that give them pleasure, or if he figures out a way to get cash-strapped families on public assistance to turn down cheap, ready-to-eat foods, he will have made significant inroads into actually making America healthy again. But getting there is going to require a lot more than a catchy slogan and some sound bites.

Gabriel Boric is the first leader in the Americas to visit the South Pole, stressing Chile's "Antarctic mission".