Pope Leo’s Trip to Latin America: What to Know Less than a month after lung surgery, Pope Leo XIV is landing in Uruguay on Friday, the first stop of a 12-day voyage across South America.

Pope Leo XIV embarks on Friday on a 12-day trip through Uruguay, Argentina and Peru. It will be the first major test of his stamina since surgeons removed a lobe of his right lung less than four weeks ago and diagnosed him with cancer.

Vatican officials and the pope’s doctors say he has sufficiently recovered, but he faces a grueling schedule of long flights and helicopter rides, encounters with massive crowds and travel through high altitudes as well as the Amazon jungle. Even with a clean bill of health, the pope will be watched closely for signs of weakness.

The trip is also a kind of homecoming for Leo. He spent two decades as a priest and bishop in Peru, where he became fluent in Spanish and was naturalized as a citizen. Though he is the first pope born in the United States, Leo has not visited the United States as pontiff and has not made firm plans to do so.

Some tensions could arise in Argentina, where the pope will meet with President Javier Milei, a right-wing politician. Mr. Milei promotes unfettered markets and the primacy of the individual over the collective, principles that many Catholics say are antithetical to their social teachings. Mr. Milei has also pitched Argentina as a sanctuary for unregulated artificial intelligence, while Leo has called for protecting the most vulnerable, including workers, from A.I.’s most disruptive effects.

In Peru, there will be another delicate backdrop, this time to his meeting with Keiko Fujimori, who won the presidency in June. Her father, Alberto Fujimori, was the country’s authoritarian leader for a decade and was later found responsible for human rights violations including murder and aggravated kidnapping. As a priest, the pope protested this violence at a time when Ms. Fujimori served as her father’s first lady. Why is the trip starting in secular Uruguay?

Uruguay, where Leo will stay until Sunday, is the least religious country in South America, according to Latinobarómetro, a poll conducted by an independent Chile-based research group. Church and state were formally separated more than a century ago, and only a third of Uruguayans identify as Catholic, the lowest rate in Latin America, according to the poll. Uruguay was the first country in Latin America to decriminalize abortion and legalize euthanasia, all policies opposed by the Roman Catholic Church. Given these factors, “it is striking that the pope is coming,” said Lilián Abracinskas, a left-wing senator in Uruguay.

Yet Leo’s visit fits a pattern.

As well as touring Catholic heartlands, the pope has made a point of traveling to places where Catholicism has waned, including France, a secular country that the pope visited in September. Although he admonished the French government for legalizing medically assisted dying, larger crowds than expected hailed the pope when he celebrated Mass in Paris. Some expect secular Uruguay to welcome Leo as a humane voice in a world grappling with rapid change.

Even for those who are not Catholic, “they yearn for some kind of moral truth,” said Professor Christopher D. Tirres, an expert on Latin America at Santa Clara University. What is the symbolism of the visit to Argentina? Argentina was the homeland of Leo’s predecessor, Francis, who served as archbishop of Buenos Aires.

It is striking that Leo, who tours Argentina from Sunday through Wednesday, is visiting there so soon after his election, particularly given that Francis never returned home during his 12 years as pope. Some experts see symbolism in Leo’s decision to visit a prison and a facility for the disabled in Buenos Aires.

They are the types of institutions that have suffered funding cuts under Mr. Milei, as well as ones that Francis might have chosen. Leo is “making a statement there,” said Andrew Chesnut, a historian specializing in Latin America and Catholicism at Virginia Commonwealth University.

Simply by visiting the kinds of institutions and people that Mr. Milei’s policies disregard or defund, Mr. Chesnut said, Leo will be showing solidarity with them and trying “to provide a contrast.”

What will Leo’s return to Peru look like? When he arrives on Wednesday, Leo is likely to be welcomed as a star in Peru, the country he first worked in as a missionary and later returned to as a bishop.

Peru is also where the pope may face his biggest health challenges.

He plans to travel to Cusco, a site considered the gateway to the mountainous ruins at Machu Picchu, more than 11,000 feet above sea level. He will also fly by helicopter to Santa Cruz de Succhabamba, a rural area in the Andes. Last week, he skipped a helicopter ride in Italy to support his recovery. “You never know how the lungs are going to perform until you stress it, add altitude,” said Dr. Roy Herbst, a lung cancer specialist and head of the cancer institute at Dartmouth.

But, Dr. Herbst added, “he’s a fit guy” who has had excellent medical care. “He’s the pope,” said Dr. Herbst. “His mission is to be out there.”Tomer Urwicz contributed reporting from Montevideo, Uruguay. Motoko Rich is the Times bureau chief in Rome, where she covers Italy, the Vatican and Greece.

Emma Bubola is a Times reporter covering Argentina.

She is based in Buenos Aires.

Julie Turkewitz is the Andes Bureau Chief for The Times, based in Bogotá, Colombia, covering Colombia, Venezuela, Bolivia, Ecuador and Peru.