NEW YORK — Federal authorities announced terrorism charges Wednesday against a leader of MS-13, continuing a nationwide crackdown against a notorious street gang that President Donald Trump described as “vile and evil.”

An indictment unsealed in Virginia against Melgar Diaz marked the first time the Justice Department has brought terrorism charges against a member of MS-13. Attorney General William Barr described Diaz as “the person who would green-light assassinations” for the gang in the United States.

It was not immediately clear whether Diaz had a defense attorney who could comment on the charges.

Prosecutors also said they would seek the death penalty against Alexi Saenz, another MS-13 leader on Long Island, New York, charged in seven killings, including those of two high schools students slain with a machete and a baseball bat. A lawyer for Saenz declined to comment.

“We believe the monsters who murder children should be put to death,” Trump told reporters at the White House, adding his administration would not rest before bringing every member of the gang to justice. “There’s never been any move like this before.”

The announcement came a day after grand juries in New York City and Nevada handed up new charges against nearly two dozen MS-13 members, ranging from drug dealing and kidnapping to murder and racketeering.

Barr said the prosecutions are part of the government’s efforts to dismantle a gang he likened to a “death cult.”

Also known as Mara Salvatrucha, MS-13 is considered one of the top transnational organized crime threats in the United States.

The organization is unique, Barr said, in that it is driven not by “commercial interests” but sheer bloodlust.

“It’s about the honor of being the most savage, bloodthirsty person you can be and building up a reputation as a killer,” Barr said.

MS-13 is believed to have been founded as a neighborhood street gang in Los Angeles in the mid-1980s by immigrants fleeing a civil war in El Salvador. The gang recruits young teenagers from El Salvador and Honduras, though many gang members were born in the U.S.

“The only way to defeat MS-13 is by targeting the organization as a whole, focusing on the leadership structure and deploying a whole-of-government approach against a common enemy,” said John Durham, a federal prosecutor in New York who directs a special task force targeting the gang.

Trump, who visited Long Island in 2017 to address the gang problem, has blamed the violence and gang growth on lax immigration policies.

The president said Wednesday that U.S. Immigration and Customs has arrested more than 2,000 MS-13 members over the past few years.

“We’ve taken them out by the thousands,” he said.

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