Our other top story tonight, the U.S. government charged the Air National Guardsman accused of leaking classified information with two charges under the Espionage Act.

Airman Jack Teixeira made his first appearance in a Boston court today, as President Biden directed the military and intelligence community to limit the distribution of sensitive information.

Nick Schifrin starts our coverage.

NICK SCHIFRIN: He appeared in front of a federal judge, the 21-year-old who followed his family into the military now accused of exposing the military's secrets.

Jack Teixeira joined the Air National Guard in September 2019 and was assigned to Otis Air National Guard Base in Massachusetts and the 102nd Intelligence Wing, which consolidates and analyzes intelligence for senior military commanders and receives near-real-time imagery collected by drones and spy planes from around the world.

MAN: As a cyber transport system specialist in the Air National Guard, your job is to make sure everybody else has the opportunity to finish their mission and save lives.

NICK SCHIFRIN: That's the job that Teixeira had, not an intelligence analyst, but a cyber transport systems journeyman, an I.T.

specialist.

To maintain the network, court documents today confirmed he had a top secret clearance and sensitive compartmented access, or SCI, to other highly classified programs since 2021, when he was called to active duty.

The documents detail how, in December, Teixeira began posting the text of classified documents.

But he was concerned he would be discovered, so, in February, he accessed this particularly sensitive document mentioned in court filings, and one day later allegedly posted a photograph of it.

Today, President Biden said the military and intelligence community would limit the distribution of sensitive information, and defense officials told "PBS NewsHour" the Joint Staff was already reviewing its distribution lists.

Teixeira could face decades in prison.

U.S. law says the unauthorized disclosure of top secret information reasonably could be expected to cause exceptionally grave damage to national security.

Attorney General Merrick Garland: MERRICK GARLAND, U.S. Attorney General: People who sign agreements to be able to receive classified documents acknowledge the importance to the national security of not disclosing those documents, and we intend to send that message, how important it is to our national security.

NICK SCHIFRIN: Teixeira posted on Discord, a social media site popular among gamers.

Today, court documents revealed Discord provided the FBI with details of Teixeira's account and the private group he administered, where he originally posted the documents.

It's a fall from grace for a proud military family.

His mother posted these photos online.

And that's his stepfather, retiring in 2019 from the same Massachusetts Air National Guard unit after a 34-year career.

QUESTION: What do you think he was trying to accomplish?

NICK SCHIFRIN: But, today, outside the courthouse, his father faced a media gauntlet, his son accused of exposing the very information he was assigned to maintain.

For the "PBS NewsHour," I'm Nick Schifrin.

GEOFF BENNETT: So, how does the U.S. government determine who should have access to secure computer networks and the information on those networks?

For that, we turn to retired Special Agent Frank Montoya, who served 26 years in the FBI, and Heidi Beirich, co-founder of the Global Project Against Hate and Extremism.

With a welcome to you both, Frank, Jack Teixeira was a cyber transport systems journeyman, what we civilians would call an I.T.

specialist.

Help us understand how he would have had access to such sensitive top secret material.

FRANK MONTOYA JR., Former FBI Official: Well, just like the promo said, the young man who was presenting that information said they're the backbone.

They're the guys that manage the communications networks on which all of this information is stored, is transmitted, is collected.

And so, in that regard, he has access to that kind of information, kind of like a systems administrator, with not as many privileges perhaps, but still very much involved in the actual management and storage and transmission of that data.

GEOFF BENNETT: And, Heidi, Teixeira was granted a top secret security clearance in 2021.

And according to the federal complaint, that means he would have signed a lifetime binding nondisclosure agreement acknowledging that leaking protected information could result in criminal charges.

Should he have had a security clearance, based on the current standard and what we now know about his background?

HEIDI BEIRICH, Global Project Against Hate and Extremism: Well, it really depends on whether or not the kinds of things he was posting online were inaccessible to the Pentagon to find.

But, if they weren't, then he should not have had a clearance.

You cannot trade in racism and antisemitism, as he did, and have clearances.

And, in fact, the clearance system was tightened up in the summer of 2021 to provide continuous monitoring of social media.

So how he slipped through that net, I think, is unclear, but he really shouldn't have.

GEOFF BENNETT: Frank, is it possible for the government to continuously monitor all of the people who have security clearances to make sure that they're living up to the standard that people with security clearances are supposed to live up to?

FRANK MONTOYA JR.: Yes, it's a terrifically challenging task, especially when you look at the kinds of information that people have access to on a daily basis off duty, as well as on duty.

I mean, one of the challenges that we faced after the Snowden disclosures when we were trying to get a handle on who has information and how they handle it and how we can protect it from being illegally disclosed was trying to -- especially in the age of the Internet and social media, was trying to develop guidelines so that we can look at, continuously evaluate their accesses, not only on their government systems, but also when they're working -- when they're at home, when they're surfing the Internet.

And that's a bigger challenge for a lot of reasons, one, because there's so many people with clearances, but also because of First Amendment concerns.

We -- it's important that, even when you join the community, and you do surrender a lot of your personal freedom or personal rights, as far access to information is concerned, you still have First Amendment rights as an American off duty, or when you're not at work.

And there's not a lot of management or control over what you might see or not see on the Internet.

And this is a classic example of that.

GEOFF BENNETT: Heidi, I know you say that this Jack Teixeira case serves as an example of the ways in which young people are radicalized online, and that he is in many ways typical of the people that you track.

In what ways?

HEIDI BEIRICH: Yes, I mean, a young mail involved in gaming culture.

He was posting this on a private server on the Discord system, which is used by gamers.

He apparently was using this classified material to show off to his friends there, who were very young, some of them teenagers, and that's where they were trading and racist memes and posting all kinds of things about guns and so on.

And this, unfortunately, is very typical.

We have a lot of young people getting radicalized in this way.

GEOFF BENNETT: Frank, this trove of leaked Pentagon documents, they were circulating apparently online for months, without it being discovered by the U.S. government.

Why didn't the federal government notice the leaked documents until it was apparent in the news media?

FRANK MONTOYA JR.: Yes, I mean, this is just kind of an old school espionage kind of thing.

I'm not saying that he committed espionage.

It was -- the charges are about unlawful retention and removal of classified information.

But he was looking at it at the work site.

And then he was taking notes and then writing stuff down.

And then, later, he was taking out specific documents out of the workspace and taking them home or photographing them, and I would imagine returning them back to the workspace, so that it was harder to track how that kind of stuff is monitored.

Or it's always harder to monitor things that way, because the emphasis is on looking on the computer networks, what -- the digital trails, that -- what you're looking at, downloading, maybe printing out on your printer or on a copy machine.

And this was stuff that he had access to, that he could look at in hardcopy, and then was, again, smuggling out of -- smuggling it out of the workspace, taking photos at home, and then bringing it back, and so much more like an old school in the way that he was doing it, and harder to monitor, because was the workspace doing bag checks at the end of the day?

Probably not because of concerns about First Amendment rights again and personal freedoms.

And so, yes, very difficult to monitor this kind of activity.

And then he's posting it on these close-hold Internet social media networks, platforms, where only a small group of people know about it.

And, in fact, if that one individual hadn't posted it on other sites, we still probably wouldn't know about it.

GEOFF BENNETT: Heidi, all of this speaks to the question of, how can the U.S. better defend against the insider threat?

HEIDI BEIRICH: Well, that's exactly right.

The insider threat is the issue here.

And I think, if we don't get a hold better on what's happening on social media, and enforce the new rules that were actually put in place on this front a couple of summers ago, we may find this again.

And I would just like to add that extremist people with racist and antisemitic beliefs and so on, they are a particular threat when it comes to insider threats.

And that's what we have seen in this case, and it's what we have to be worried about in terms of domestic extremists being in the military.

GEOFF BENNETT: Heidi Beirich is co-founder of the Global Project Against Hate and Extremism, and Frank Montoya is a retired FBI special agent.

My thanks to you both.

FRANK MONTOYA JR.: Thank you.