For at least a decade, rumors have swirled in Venezuela that the United States is going to swoop in with troops in and topple the country’s autocrat, Nicolás Maduro. The troops have never arrived, and Washington-backed efforts to replace him have failed.

So this week, when the Trump administration began a major buildup of U.S. naval forces outside the South American nation — prompting questions about whether President Trump is once again planning for regime change — Venezuelans responded with a bit of fear and anxiety, but mostly well-earned skepticism.

“I sincerely don’t believe the American government will do anything,” said Pedro Martínez, 52, a driver in the city of Carabobo, near the country’s northern coast. “They make their announcements, but nothing happens. We’ve been doing this for many years, and we Venezuelans no longer believe anyone, neither here nor there.”

The Pentagon began moving U.S. Navy assets, including warships, into the southern Caribbean Sea recently, after Mr. Trump issued a still-secret directive calling on the military to use force against Latin American drug cartels, including a Venezuelan group called the Cartel de los Soles.

Officials in the Trump administration have said the buildup was part of an effort to stop drugs from flooding into the United States, while also calling Mr. Maduro an illegitimate leader.

In response, Mr. Maduro said on Monday that he was deploying 4.5 million militiamen around the country. “No empire will touch the sacred soil of Venezuela, nor should it touch the sacred soil of South America,” he said.

The militia force Mr. Maduro was referring to is made up of volunteers and is the least battle-ready of the country’s military branches, said Carolina Jiménez Sandoval, president of the Washington Office on Latin America, a research organization.

Credible data on anything in Venezuela is hard to come by. But Ms. Jiménez Sandoval said it wasn’t plausible to think the militia has so many members. Venezuela’s population is about 28 million people. She called the Mr. Maduro’s numbers “a boisterous way of showing power.”

“I don’t think he expects people to truly believe that,” she added.

As many as three guided-missile destroyers will soon arrive in the region, according to U.S. officials, who have said that the warships will target boats operated by drug cartels transporting fentanyl to the United States.

Venezuela has a long and established role as a transit hub in the cocaine trade. But there is no evidence that fentanyl is being produced in the region, said Diego Garcia-Devis, a global drug policy expert at Open Society Foundations.

The motivations behind the U.S. military mobilization are not entirely clear.

Luz Mely Reyes, a prominent Venezuelan journalist, said that Mr. Trump may be trying to pressure Mr. Maduro into negotiating his exit.

Ms. Jiménez Sandoval said Mr. Trump may be trying to show his dominance in the region — not just to Venezuela, but to key regional players like Mexico and Colombia.

“Trump still has a very strong, big superpower mentality, although he considers himself an isolationist,” she said.

Rumors of possible U.S. military involvement in Venezuela were last strongest in 2019 and 2020, when the first Trump administration publicly backed a young Venezuelan legislator, Juan Guaidó, calling him the country’s rightful leader.

In April 2019, Mr. Guaidó appeared alongside soldiers at a military base and called on the population to rise up against Mr. Maduro. But the uprising never materialized, and Mr. Guaidó eventually fled the country — to the United States.

This and other failed efforts to oust Mr. Maduro (including a 2020 coup attempt by a former U.S. Green Beret) have made many Venezuelans doubt that change will come from the outside.

Skeptics include Elsa Pérez, 43, who sells cosmetics and clothing in Carabobo.

“I stopped believing in gringos since the time of Juan Guaidó’s lies, which made us think there would really be a change of government,” she said on Friday. “And what happened? Nothing at all.”

State television channels this week broadcast images of Mr. Maduro giving a speech to members of the military wearing fatigues, and highlighted messages of support from China and Russia, as Venezuela confronted what the president called the “gringo empire.”

One newscaster on the channel Telesur accused the United States of engaging in “psycho-terror.”

In the past, threats to Mr. Maduro’s power have resulted in significant crackdowns on the civilian population. Last year, after an opposition figure, Edmundo González, appeared to beat him in a presidential election, he sent the military and paramilitary gangs called colectivos into the streets. About two dozen people died and some 2,000 were arrested, many of whom remain in custody.

Venezuelan officials have often accused the protesters of being directed by outside forces, including the United States.

This week, even as people watched nervously for signs of domestic repression, the country’s best-known website for political satire, El Chigüire Bipolar, found some levity in the situation.

One headline read: “Respected journalist who claimed the Marines were coming in 2014, 2015, 2016, 2017, 2018, 2020, 2021, 2022, 2023 and 2024 confirms they are coming in 2025.”

Genevieve Glatsky contributed reporting from Bogotá, Colombia.