Just a decade ago, the era of U.S. wars, coup plots and military interventions in Latin America seemed to be ebbing when the Obama administration declared that the Monroe Doctrine, which long asserted U.S. military supremacy in the Americas, was dead.

Now this cornerstone of foreign policy is roaring back to life, resurrecting fears over U.S. military interference in the region after President Trump ordered the Pentagon to use military force against certain Latin American drug cartels.

Leaders in the region are still trying to decipher what Mr. Trump’s order could mean. Mexico and Venezuela, two nations where the administration has designated cartels within their borders as terrorist groups, seem especially vulnerable.

But up and down much of Latin America, any whisper of reviving such actions could also unleash a chain reaction resulting in a surge in anti-American sentiment. The news of Mr. Trump’s order has already intensified a wariness against intervention from abroad, even in Ecuador and other countries plagued by violent drug wars in recent years.

“I’m a right-wing conservative, so I want armed citizens and the military actually shooting,” said Patricio Endara, 46, a businessman in Quito. “But I wouldn’t agree with having foreign soldiers in Ecuador.”

That skepticism draws from the bitter memories left by the long record of U.S. military interventions in the region, whether through direct or indirect action, as during Colombia’s long internal war.

“Those are formulas that have shown, to the point of exhaustion, their failure,” Iván Cepeda, a Colombian senator, said in an interview.

These kinds of interventions “inflict immense damage,” said Fernando González Davidson, a Guatemalan scholar, pointing to how such actions often strove for regime change. “The U.S. leaves power in the hands of a corrupt and criminal class aligned with its own interests.”

A U.S.-backed coup in 1954 in Guatemala ousted a democratically elected leader over concerns that a land reform project threatened the United Fruit Company, a powerful American corporation with large tracts of land there.

In the decades that followed, that Guatemalan coup became a rallying cry across the region by exposing U.S. Cold War policy as a tool for protecting U.S. interests over democratic principles and national sovereignty.

Long before the U.S. military’s involvement in the region became so contentious, President James Monroe’s assertion in 1823 that the United States could use its military in Latin America had more bark than bite, historians say.

The United States at the time lacked the power to do much intervening. Concerns over European meddling in the hemisphere, one of the doctrine’s early features, soon eased when it became clear that European powers, dealing with their own internal challenges, could not easily recolonize newly independent Latin American nations.

But in the 1840s, President James K. Polk invoked the doctrine to justify the Mexican- American War, which produced the U.S. conquest of Mexican lands now comprising states such as California, Arizona, Colorado and New Mexico.

That humiliating outcome, and other U.S. military interventions in Mexico in the 1910s, profoundly shaped Mexico’s political identity, fostering a strong sense of nationalism that is often in opposition to the United States.

President Claudia Sheinbaum of Mexico tapped into such sentiment on Friday when she rejected the use of U.S. military forces in her country. She made it explicitly clear that Mexico has ruled out any kind of “invasion.”

“Unilateral U.S. military action inside Mexico would be disastrous for bilateral cooperation on issues like migration and security,” said Arturo Santa-Cruz, an expert on U.S.-Mexico relations at the University of Guadalajara.

Territorial expansion came into play again during the Spanish-American War in 1898, solidifying the United States’ emergence as a global power when it took Puerto Rico, Guam and the Philippines from Spain.

President Theodore Roosevelt followed in 1903 by sending warships to support a revolt by separatists in Colombia. They formed Panama and gave the United States control over the “Canal Zone,” which Panama fully regained only in 1999.

President Roosevelt created his own corollary to the Monroe Doctrine the next year, claiming that the United States should exert “police power” in the Americas when it found cases of flagrant “wrongdoing.”

This pivot turbocharged U.S. interventions, and protecting American property often was the justification. In Cuba alone, U.S. forces intervened on three occasions from 1906 to 1922.

Elsewhere in the Caribbean, U.S. forces occupied Haiti from 1915 to 1934, establishing a pro-American government. American soldiers similarly occupied the Dominican Republic from 1916 to 1924, partly to manage the national debt owed to American creditors.

In Central America, Honduras saw repeated U.S. military landings in the 1910s and 1920s, and U.S. forces occupied Nicaragua from 1912 to 1933, partly to prevent any other nation from building a Nicaraguan Canal.

During the Cold War, the United States found new ways to intervene. This included supporting coups that ousted democratically elected leaders in Guatemala, Brazil and Chile.

U.S. forces also kept intervening with boots on the ground in places such as the Dominican Republic and in Grenada, driven by concerns about communists in these countries.

So many interventions had the effect of unifying much of Latin America around the issue of sovereignty. Such positioning was on display when Latin American countries recently closed ranks to oppose Mr. Trump’s threats to regain the Panama Canal.

“There’s been an iron will among Latin Americans to define one of their core values as national sovereignty and nonintervention,” said Alan McPherson, a historian at Temple University.

Even as the Cold War was easing in 1989, the United States once again intervened in Panama to depose its de facto leader, Manuel Noriega, who was wanted by the U.S. authorities on drug trafficking charges.

For the Americans, it was “Operation Just Cause,” said Efraín Guerrero, a community leader who gives walking tours in Panama City to keep alive the memory of the U.S. invasion. “But for us, it became ‘Forgetting Forbidden,’ because we have to remember all those who died.”

That intervention could provide a template for a similar action in a country like Venezuela, where the United States has doubled a reward, to $50 million, for information leading to the arrest of its leader, Nicolás Maduro, whom U.S. officials accuse of links to gangs like Tren de Aragua and the Sinaloa Cartel in Mexico.

Mr. Maduro responded on Friday to Mr. Trump’s order by accusing the United States of trying to create wars. “Anyone who messes with Maduro, and with Venezuela, will be destroyed forever,” Mr. Maduro said.

A military intervention in a relatively large country like Venezuela (or for that matter, much larger Mexico) would also be a break from precedent. Generally the United States has opted to intervene in smaller countries in Central America and the Caribbean, wary of the pitfalls involved in sending forces into larger nations.

But since the news of Mr. Trump’s move appeared on Friday, some critics of the Venezuelan regime have called for the U.S. military to do just that, asking the U.S. president to order U.S. troops to go after Mr. Maduro, just as they targeted Panama’s president in 1989.

“Let’s hope he does it,” said a Venezuelan woman in the city of Maracaibo, who asked that her name not appear for fear of Mr. Maduro. “This is what we have been waiting for, for years — for Maduro to leave or for Trump to take him. We Venezuelans would happily give him away.”

“This move or threat by the Trump administration,” said Christopher Sabatini, a Latin America expert at the London-based Chatham House, “is going to really touch that historic and deeply felt popular nerve” about U.S. interventions in Latin America. However, he said, throughout history there was also, often, “a particular sort of partisan faction that was lobbying the United States to get involved.”

Jody García contributed reporting from Guatemala City, and José María León Cabrera from Quito, Ecuador.