That's where an FBI tactical team took 21-year-old Airman First Class, Jack Teixeira, into custody this afternoon.

Attorney General Merrick Garland announcing the arrest of Teixeira in the investigation into the retention and transmission of classified National Defense information.

Teixeira, as a member of the intelligence wing of the Massachusetts Air National Guard, though it's unclear what his authorized level of access was.

The leaked documents include American assessments of Russian capabilities in Ukraine and also expose US spy efforts against allies.

Lots of questions about all this tonight. Andrea Mitchell starts us off with what we know.

Tonight, backed up by an armored SWAT vehicle with guns drawn, the FBI arrested a 21-year-old Airman First Class in the Massachusetts National Guard working in IT in their intelligence wing, who the government says is the source of that major intelligence leak.

"Today, the Justice Department arrested Jack Douglas Teixeira in connection with an investigation into alleged unauthorized removal, retention, and transmission of classified National Defense information."

The Washington Post was first to report that Teixeira, under the moniker OG, shared classified intelligence - including photos of elite documents - in a private group of mostly young men on Discord, an online chat platform popular with video gamers.

The Post spoke with an anonymous member of that chat room, populated by gun enthusiasts who frequently shared racist memes.

"I don't think that there was a goal nor some sort of accomplishment that he was looking for in sharing these documents. Of course, there's some anti-government sentiment."

Teixeira had enlisted three and a half years ago.

The anonymous group member told the Washington Post he was a natural leader but not a whistleblower.

"OG was not hostile to the US government. He had disagreed on several occasions such as Waco and Ruby Ridge and thought that the government is overreaching in several aspects.

There was no heavy Snowden-like conspiracy here like some people may believe."

The leaked intelligence was online for months, with photos of classified documents visible for weeks.

"Some of it was in public."

"Right. Clearly, the administration was slow on the uptake. How was it not discovered and how is it that an individual like this could have the access that they did?"

In Ireland, President Biden downplayed the impact.

"I'm not concerned about the Reaganism, I'm concerned that it happened, but there's nothing contemporaneous that I'm aware of that is of great continent.

According to the New York Times today, one of the leagues reveals broad infighting inside the Kremlin over the scale of their casualties in Ukraine.

And the Washington Post is reporting that the US expects the war to continue into next year.

Kristen Welker asked Poland's prime minister about that.

"Is that your assessment?"

"I think so too because Russia has huge and vast natural resources, human resources."

Now, the Pentagon is reviewing who has access to top secrets.

"We do have stringent guidelines in place for safeguarding classified and sensitive information. This was a deliberate criminal act, a violation of those guidelines, and if there are any areas where we need to tighten things up, we certainly will."

And Andrea, how does it happen that a low-ranking National Guardsman has access to so many of our country's secrets?

That is exactly what the House Intelligence Chairman told me. They are going to be asking at an oversight hearing as well as why they're not monitoring social media more effectively.

Whatever to share his motive, the Attorney General indicated he is now facing serious charges under the Espionage Act, and that means he could face very serious penalties if he's convicted.

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