Stewart Rhodes, the leader of the Oath Keepers, was sentenced to 18 years in prison on Thursday for his role in January 6 riot at the Capitol.
Rhodes had been convicted of seditious conspiracy in a landmark criminal trial in November that sealed the Justice Department's ability to hold the rioters accountable and validated arguments that the breach of Congress was a threat to democracy.
He was also found guilty of obstructing an official proceeding and tampering with documents.
And on Thursday, District Court Judge Amit Mehta ruled that Rhodes' actions on January 6 even amounted to domestic terrorism.
He said that Rhodes was the mastermind behind the Oath Keepers' breach of the Capitol, claiming the group would not have stormed the building and interrupted Congress' certification of the 2020 presidential election if not for him.