What FBI agents will now being looking for

As a member of the Massachusetts Air National Guard was arrested in connection with the leak of classified US documents, agents were seen in aerial footage directing the 21-year-old suspect to move toward an armored vehicle with his hands on his head. CNN's Josh Campbell said the apparent "overwhelming show of force" was used because of the suspect's background in the military.

Agents took extra precautions because the report disclosed him being a gun enthusiast, Campbell said.

The next steps, Campbell said, is investigating the residence of the suspect, which is now considered a crime scene.

"The feds will be there for a long time, because of course they need to determine: Are there additional classified documents that are inside that residence? [According to] what we've seen in past cases, the feds will get their search warrants lined up ahead of time in order to go in and search that top to bottom," he said.

Agents will be on the lookout for any location where a computer, a phone or digital files could be stored, Campbell said

Pentagon spokesperson Brig. Gen. Patrick Ryder said the leaking of a trove of classified information on social media sites was a "deliberate criminal act," and the department is looking at how it protects such information.

"We continue to review a variety of factors as it relates to safeguarding classified materials. This includes examining and updating distribution lists, assessing how and where intelligence products are shared and a variety of other steps. I would say, though, that it is it is important to understand that we do have stringent guidelines in place for safeguarding classified and sensitive information," Ryder said.

"And so, again, I think that's important to understand that we will continue to do everything we can to ensure that the people who have a need to know, when it comes to this kind of information, have access to that. We're always going to learn from every situation. But again, this is something that will continue to look at," he continued.

According to a US official familiar with the matter, law enforcement have arrested Jack Teixeira, a 21-year-old member of the Massachusetts Air National Guard, on Thursday in connection with the leaking of classified documents.

When asked about the 21-year-old, Ryder said he would not discuss the particular case, but said if someone requires a security clearance after joining the military, they go through "the proper vetting."

"We entrust our members with a lot of responsibility at a very early age," he said.

"So you've received training, and you will receive an understanding of the rules and requirements that come along with those responsibilities," Ryder added. "And you're expected to abide by those rules, regulations and responsibility; it's called military discipline."

Jack Teixeira is arrested on Thursday. (WBZ)

The FBI arrested Jack Teixeira Thursday in connection with the leaking of classified documents that have been posted online, according to a US official familiar with the matter. 

Teixeira, 21, is a member of the Massachusetts Air National Guard. His arrest comes following a fast-moving search by the US government for the identity of the leaker who posted classified documents to a social media platform popular with video gamers.

Teixeira was first identified by The New York Times Thursday ahead of his arrest as the leader of the group where a trove of classified documents was posted.

Jack Teixeira is seen in this photo taken from Instagram. (From Instagram)

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Pentagon spokesperson Brig. Gen. Patrick Ryder speaks during a media briefing on Thursday. (Alex Brandon/AP)

The Pentagon declined to comment on reports of an impending arrest of the suspected leaker of classified intelligence documents Thursday, saying only that the Pentagon and other agencies are working “around the clock” to get a better sense of the leak. 

He said officials are working with other agencies and the intelligence community to "better understand the scope, scale, and impact of these leaks."

"Just as we're limited in what we can say about the DOJ’s ongoing investigation will be also very limited in what we can say about any of the documents themselves," Ryder said.

Law enforcement is expected to soon arrest a member of the Massachusetts Air National Guard in connection with the leaking of classified documents that have been posted online, according to a law enforcement source.  

The guardsman is 21-year-old Jack Teixeira, according to the New York Times, which reported that he is the leader of an online gaming group where a trove of classified documents was posted.

Some background: The FBI had narrowed the number of people who they believe could be responsible for the leaks and have been conducting interviews in recent days, two people briefed on the matter said earlier.

While there's a large number of people who had access to the documents, investigators have been able to home in on a small number for closer scrutiny, thanks to the forensic trail left by the person who posted the documents. Investigators are working on building a case for prosecution, people familiar with the matter say. 

A major leak of classified Pentagon documents has rattled US officials, members of Congress and key allies in recent days.

Now a criminal investigation is being led by the FBI’s Washington field office to find who is responsible. The FBI had narrowed the number of people who could have leaked the information and have been conducting interviews in recent days, two people briefed on the matter said earlier. 

What we know about what happened: The documents appeared online last month on the social media platform Discord, according to screenshots of the posts reviewed by CNN.

The posts are photos of crumpled documents laid on top of magazines and surrounded by other random objects, such as zip-close bags and Gorilla Glue. It is as if they had been hastily folded up and shoved into a pocket before being removed from a secure location, a source familiar with these kinds of documents told CNN.

A Discord spokesperson confirmed in a statement Sunday that they are cooperating with law enforcement on the investigation.

Those documents discovered on Friday all bore classified markings, some top secret — the highest level of classification.

Some of the documents, which US officials say are authentic, expose the extent of US eavesdropping on key allies, including South Korea, Israel and Ukraine. Others discuss Russia's war in Ukraine.

Ukrainian servicemen fire at Russian positions in the Donbas region last month. (Aris Messinis/AFP/Getty Images)

Leaked Pentagon documents contain a wide range of highly classified information – providing a rare window into how the United States spies on allies and adversaries alike.

CNN has reviewed 53 leaked documents, all of which appear to have been produced between mid-February and early March.

Some of the documents, which US officials say are authentic, expose the extent of US eavesdropping on key allies, including South Korea, Israel and Ukraine.

On Russia and Wagner Group: Others reveal the degree to which the US has penetrated the Russian Ministry of Defense and the Russian mercenary organization Wagner Group, largely through intercepted communications and human sources, which could now be cut off or put in danger.

On Ukraine's military and Zelensky: Still, others divulge key weaknesses in Ukrainian weaponry, air defense, and battalion sizes and readiness at a critical point in the war, as Ukrainian forces gear up to launch a counteroffensive against the Russians – and just as the US and Ukraine have begun to develop a more mutually trusting relationship over intelligence-sharing.

One document reveals that the US has been spying on Ukrainian President Volodymyr Zelensky. That is unsurprising, said a source close to Zelensky, but Ukrainian officials are deeply frustrated about the leak.

The US intelligence report, which is sourced to signals intelligence, says that Zelensky in late February “suggested striking Russian deployment locations in Russia’s Rostov Oblast” using unmanned aerial vehicles since Ukraine does not have long-range weapons capable of reaching that far.

Signals intelligence includes intercepted communications and is broadly defined by the National Security Agency as “intelligence derived from electronic signals and systems used by foreign targets, such as communications systems, radars, and weapons systems.”

On South Korean officials: Yet another document describes, in remarkable detail, a conversation between two senior South Korean national security officials about concerns by the country’s National Security Council over a US request for ammunition.

The officials worried that supplying the ammunition, which the US would then send to Ukraine, would violate South Korea’s policy of not supplying lethal aid to countries at war. According to the document, one of the officials then suggested a way of getting around the policy without actually changing it – by selling the ammunition to Poland.

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The Pentagon is seen from the air in this March 2022 file photo. (Joshua Roberts/Reuters/File)

The Pentagon has begun to limit who across the government receives its highly classified daily intelligence briefs following a major leak of classified information discovered last week.

Some US officials who used to receive the briefing materials daily have stopped receiving them in recent days, sources familiar with the matter told CNN, as the Pentagon’s Joint Staff continues to whittle down its distribution lists.

The Joint Staff, which comprises the Defense Department’s most senior uniformed leadership that advises the president, began examining its distribution lists immediately after learning of the trove of leaked classified documents – many of which had markings indicating they were produced by the Joint Staff’s intelligence arm, known as the J2.

All the email lists have been reviewed, a senior defense official said, and some restrictions may only be temporary. Everyone on the lists had proper clearance, but not everyone needs to receive that information daily, the official added.

Pentagon spokesperson Brig. Gen. Pat Ryder in a Wednesday interview with News Nation that the Pentagon is looking at “mitigation measures in terms of what we can do to prevent potential additional unauthorized leaks.”

The leaked documents have exposed what officials say are lingering vulnerabilities in the management of government secrets, even after agencies overhauled their computer systems following the 2013 Edward Snowden leak, which exposed the scope of the National Security Agency’s intelligence gathering apparatus.

It is unlikely, however, that those safeguards would have prevented the most recent leak, sources said. The documents that circulated online appear to have been printed largely from briefing books that staffers spend hours putting together for senior officials on the Pentagon’s Joint Staff.

A 21-year-old Massachusetts Air National Guardsman has been identified by The New York Times as the leader of an online gaming chat group where a trove of classified documents — which contain information about the war in Ukraine — was posted. 

The Times reported Thursday that FBI investigators want to talk to the service member and believe he has information relevant to the ongoing investigation into the leak.

CNN has not independently verified the identity of the chat leader or the FBI’s interest in talking with him. 

Earlier Thursday, President Joe Biden appeared to suggest that the US government is close to identifying the leaker.

CNN has previously reported that the Army Criminal Investigation Division is also “assisting the DoD in their investigation” of the leak, Jeffrey Castro, a spokesman for the division, told CNN.

On Wednesday, the Washington Post reported that the person behind the leak worked on a military base and posted sensitive national security secrets in an online group of acquaintances.