NORTH DAYTON, Massachusetts. — The FBI arrested a 21-year-old member of the Massachusetts Air National Guard on Thursday in connection with the leak of dozens of highly classified documents containing many national security secrets, including the breadth of US surveillance. lead to Russia.

Airman First Class Jack Douglas Teixeira has been taken into custody on charges of leaking classified documents after federal authorities said he posted batches of sensitive intelligence on an online game group called Thug Shaker Central.

When reporters from The New York Times gathered outside the house on Thursday afternoon, about half a dozen FBI agents broke into the home of Teixeira’s mother in North Daytona, with a twin-engine government spy plane on duty overhead.

Some of the agents arrived heavily armed. Law enforcement officials learned before the search that the Teixeira pilot had several weapons, according to a person familiar with the investigation, and the FBI found weapons in the house.

Shortly thereafter, cameras captured Teixeira, a pilot in handcuffs, wearing red shorts and boots, being escorted from his home by two heavily armed men.

In Washington, Attorney General Merrick B. Garland, in a brief statement, announced the arrest and said that the Teixeira airman would be taken to Federal District Court in Massachusetts. Mr. Garland said he was arrested in connection with the “unauthorized seizure, storage and transmission of classified national defense information,” a reference to the Espionage Act, which is used to prosecute mistreatment and theft of sensitive intelligence information.

The arrest raised questions about why such a junior enlisted airman had access to such an array of potentially dangerous secrets, why adequate security measures weren’t put in place after earlier leaks, and why a young man risked his freedom to share intelligence about the war in Ukraine with a group of friends. whom he knew from a video game social networking site.

The motive behind the case remains unclear. But according to people who knew him online, Teixeira’s flyer was not an informer. Unlike previous huge leaks, from the Pentagon Papers to WikiLeaks to the Edward Snowden revelations, outrage at wrongdoing or government policies didn’t seem to be a factor.

Indeed, the revelations had the potential to harm all parties in Ukraine, as well as future intelligence gathering. While some officials, including President Biden, have downplayed the damage from the leak, it will take months to find out if US intelligence is losing access to important data-gathering methods due to the disclosure.

The FBI followed the Teixeira airman for several days, tracking their own investigative evidence, as well as the same information as The Times and Washington Post According to officials, he talked about a Discord group where he shared documents.

However, as reporters got more information, law enforcement had to speed up the investigation.

While federal investigators believed the Teixeira airman could pose a danger to search agents, his online friends knew him as the sometimes aggressive leader of their small community.

A few months ago, Thug Shaker Central user aka OG started uploading hundreds of pages of intelligence briefings to a small chat room. The group also discussed weapons and military equipment, as well as their group’s original theme of video games.

While members of the chat group did not name the leader of the group, a trail of digital evidence collected by The Times led to Teixeira the airman. US officials have confirmed that they believe he uploaded information illegally taken from US military computers.

In posting the material, OG was lecturing group members who had bonded during the pandemic lockdown about the importance of staying on top of world events.

Airman Teixeira was trained as a cyber transport systems specialist, a job that could involve many responsibilities, such as keeping his unit’s communications networks up and running. He was assigned to the 102nd Reconnaissance Wing at Otis Air National Guard Base, part of Joint Base Cape Cod, according to an Air Force official. The official Facebook page of the 102nd Reconnaissance Wing congratulated Airman Teixeira and his colleagues on their July promotion to first class pilots.

Officials have not responded to questions about what Teixeira’s job as a pilot requires him to have access to daily slides about the war in Ukraine, not to mention the daily stream of intelligence reports from the CIA, the National Security Agency and the Office of the Director of National Intelligence. There are units at the base that process intelligence gathered from drones and U-2 spy planes, though it’s doubtful that the job itself would require this sort of access to the vast array of classified information that’s been leaked to the Discord server.

But he could have accessed the documents in other ways as well. Secret service-cleared US government officials often receive such documents by email over a secret computer network, one official told The Times, and the emails can then be automatically forwarded to other people.

Teixeira’s mother, Dawn, speaking in front of her home in North Daytona on Thursday, confirmed that her son was a member of the Air National Guard and said he recently worked the night shift at the Cape Cod base. he changed his phone number, she said.

Later, someone who turned out to be the pilot Teixeira drove into the compound in a red pickup truck.

When the Times reporters approached the house again, the truck was parked in the driveway. Airman Teixeira’s mother and stepfather were standing in the driveway.

When asked if the Teixeira airman was there and if he was willing to speak, his stepfather, Thomas P. Dufolt, said: “He needs to get a lawyer if things are going the way they are going now. The feds will come soon, I’m sure.”

In a few hours, Mr. Dufoe’s prediction retired air force sergeantwas confirmed when the FBI and other government officials entered the premises.

A neighbor, Paul Desouza, watched as FBI agents called out the name of the pilot Teixeira. According to the neighbor, after that the young man left the house.

Mr. Desuza did not know the Teixeira pilot, but said he often heard him firing weapons in the woods behind his house.

After the pilot Teixeira was taken away, the search of the property continued. And as the sun began to set, a food delivery truck arrived at the FBI agents searching the family home of the Teixeira airman, which meant the search was likely to continue for several more hours.

Members of Thug Shaker Central who spoke to The Times said the documents they discussed online were meant to be purely informative. Although many were linked to the war in Ukraine, the participants said they did not take sides in the conflict.

The documents, they said, only began to gain wider attention when a member of the group of teenagers took several dozen documents and posted them on a public online forum. From there, they were picked up by Russian-language Telegram channels, and then by The Times, which was the first to report them.

In Washington, the leak crisis began late last week, when some documents began to surface on Telegram and Twitter.

Secretary of Defense Lloyd J. Austin III was initially informed of the leak on the morning of 6 April. Pentagon officials tried to delete some messages on Telegram and Twitter with photos of some of the documents that were originally found, but were unsuccessful. .

The next day, last Friday, Mr. Austin began calling department-wide meetings to address the growing number of revelations. The Pentagon and other US officials have begun contacting Congressional leaders and allies to warn them of the leaks, which have sparked political storms in some countries.

Also last Friday, the Joint Headquarters of the Armed Forces, which produced many of the leaked briefing slides, put in place procedures to limit the distribution of highly sensitive briefing papers and restrict attendance at meetings where briefing books containing paper copies of documents were made available.

In his first public comments on the leaks Tuesday, Mr. Austin struggled to explain why the Department of Defense only became aware of the leaks long after they first appeared on Discord.

“Well, they were online somewhere,” Austin said of the leaked documents. “And where exactly and who had access at that moment, we do not know. We just don’t know at the moment.”

As Mr. Austin spoke, the news outlets began writing about the discovery of new documents.

On Thursday morning, Mr. Austin called a meeting with senior officials to discuss the crisis.

But by then the FBI was preparing a search warrant for the North Daytona home, and investigators were beginning to assure Pentagon officials that the whistleblower would soon be caught.

Reports and studies have been provided Riley Mellen, Adam Goldman, Michael Schwartz, Helen Cooper, Eric Schmitt, John Ismay, CJ Chivers, Michael D Shire, Kitty Bennett another Sheila McNeil.