President Trump’s executive order on Saturday invoking the Alien Enemies Act targeted Venezuelan citizens 14 years and older with ties to the transnational gang Tren de Aragua, saying they “are liable to be apprehended, restrained, secured, and removed as Alien Enemies.”

Mr. Trump’s order was quickly challenged in court, but the gang has been a growing source of concern for U.S. officials over the last year. The Biden administration labeled Tren de Aragua a transnational criminal organization in 2024, the New York Police Department has highlighted its activity on the East Coast, and the Trump White House began the process of designating it a foreign terrorist organization in January.

Here is what we know about the gang:

A rising force out of Venezuela

Tren de Aragua (Train of Aragua, or Aragua Train) has roots in Tocorón prison in Venezuela’s northern Aragua state, which the group’s leaders had transformed into a mini-city with a pool, restaurants and a zoo. They reportedly recorded executions and torture there to maintain control over other prisoners.

As Venezuela’s economy collapsed and its government under President Nicolás Maduro became more repressive, the group began exploiting vulnerable migrants. Tren de Aragua’s influence soon stretched into other parts of Latin America, and it developed into one of the region’s most violent and notorious criminal organizations, focusing on sex trafficking, human smuggling and drugs.

Colombian officials in 2022 accused the gang of at least 23 murders after the police began to find body parts in bags. Alleged members have also been apprehended in Chile and in Brazil, where the gang aligned itself with Primeiro Comando da Capital, one of that country’s biggest organized crime rings.

A recent entry to the United States

Despite the many unknowns about its true size or sophistication in the United States, Tren de Aragua has emerged as a real source of concern for law enforcement in the last couple of years.

In New York City, according to the police the gang has focused on stealing cellphones; retail thefts, especially high-end merchandise in department stores and thefts while riding scooters; and dealing a pink, powdery synthetic drug, known as Tusi, that is often laced with ketamine, MDMA or fentanyl.

The police have also said that the gang is believed to recruit members from inside the city’s migrant shelters, and has variously had conflicts or made alliances with other gangs.

In other parts of the country, people accused of affiliations with Tren de Aragua have been charged with crimes such as shootings and human trafficking, mostly targeting members of the Venezuelan community.

In May 2024, federal officials uncovered a sex-trafficking ring in which they said the gang was forcing Venezuelan women into sex to repay debts to smugglers who assisted with border crossings. The ring stretched across Louisiana, Texas, Virginia, Florida and New Jersey, according to a complaint filed in federal court.

The group’s presence in the United States was a flashpoint of the 2024 election, as Mr. Trump accused the Biden administration of letting criminals into the country. During a presidential debate, he falsely suggested that the gang had taken over Aurora, Colo.

A source of stigma for migrants

The Trump administration has repeatedly described Tren de Aragua as a focus of its deportation efforts. Venezuelan migrants seeking asylum say the gang’s presence and the discourse around it in the United States have created hurtful stigma and discrimination against them.

“Any of us who have tattoos, they think that we are Tren de Aragua,” said Evelyn Velasquez, 33-year-old Venezuelan woman, told The New York Times in September. “I’ll go apply for a job and when they hear that we are Venezuelan, they turn us down.”

In February, the White House press secretary said that 10 men detained and housed in Guantánamo Bay, Cuba were members of Tren de Aragua. The sister of one of the men detained said that he was not a gang member.

In late February, the Trump administration abruptly emptied two detention sites the government had used to hold 177 Venezuelans flown in from the United States, including a military prison building formerly used to hold terrorism detainees. Federal officials moved out a second group of migrants this month.