A 21-year-old member of the Massachusetts Air National Guard has been tied to leaking top secret U.S. documents about the Ukraine war, according to reports.

Jack Teixeira has been identified as the leader of a Discord group, a social media platform, where the highly classified military documents were posted online.

The New York Times first reported the Massachusetts Air National Guardsman’s identity on Thursday.

An arrest in the case could happen on Thursday, according to the Wall Street Journal.

A Pentagon spokesman earlier this week said the disclosures present a “very serious risk to national security,” and the Justice Department opened an investigation to identify the person responsible.

“We’re getting close,” President Biden said on Thursday. He said that though he was concerned that sensitive government documents had been disclosed, “there’s nothing contemporaneous that I’m aware of that is of great consequence.”

In a Discord forum that was originally created to talk about a range of topics, members would debate the war in Ukraine. According to one member of the chat, an unidentified poster shared documents that the poster claimed were classified, first typing them out with the poster’s own thoughts, then, as of a few months ago, uploading images of folded papers.

Herald wire services were used in this report.