WASHINGTON (Nexstar) – Days after leaked Pentagon documents became widespread on Twitter, authorities have taken one man into custody in connection with the leak.

The Justice Department confirms a member of the U.S. Airforce National Guard was arrested.

“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,” U.S. Attorney General Merrick Garland said.

While the Justice Department is leading the ongoing investigation, the Pentagon says it is taking the issue seriously and is reviewing who can access certain classified information.

“It is important to understand that we do have stringent guidelines in place for safeguarding classified and sensitive information,” Pentagon Press Secretary Airforce Brig. Gen. Pat Ryder said.

The Pentagon says the process includes the need to obtain security clearances and the signing of non-disclosure agreements.

“All indicates this was a deliberate criminal act, a violation of those guidelines,” Ryder added.

Because of the early stage of the investigation, it’s unclear whether others in the chain of command could also be held responsible for the leak.

However, Massachusetts Democratic Congressman Jake Auchincloss says the U.S. first has to make sure the leak doesn’t jeopardize Ukraine’s defense against Russia and “how do we do our utmost as a nation to support the Ukrainian counteroffensive this spring.”

Texiera was taken into custody without incident and will have an initial appearance at the U.S. District Court for the District at Massachusetts.