President Trump asserted on Friday that his 2016 campaign had been “conclusively spied on,” calling the the actions “treason,” and suggesting that those behind it be given prison time.

“My Campaign for President was conclusively spied on. Nothing like this has ever happened in American Politics. A really bad situation. TREASON means long jail sentences, and this was TREASON!” Trump tweeted.

Trump’s statement follows Attorney General William Barr’s testimony before the Senate Judiciary Committee that “spying did occur” against the Trump campaign in 2016.

The Department of Justice is now pursuing multiple investigations into how intelligence activities surrounding  the Trump campaign got started and whether proper FBI procedures were followed. Earlier this week, Barr appointed John Durham, U.S. District Attorney from Connecticut, to lead the review of the FBI’s conduct, including “all intelligence collection activities,” during the early stages of the Bureaus’s investigation into Trump’s 2016 campaign. 

Barr first announced his intentions on Capitol Hill last month, stating on April 9, “I am reviewing the conduct of the investigation and trying to get my arms around the aspects of the counterintelligence investigation that was conducted in the summer of 2016.”

“Government power was used to spy on American citizens,” Barr told the Wall Street Journal on Friday. “I can’t imagine any world where we wouldn’t take a look and make sure that was done properly.”

“I’ve been trying to get answers to the questions and I’ve found that a lot of the answers have been inadequate and some of the explanations I’ve gotten don’t hang together, in a sense I have more questions today than when I first started,” Barr added in his interview with Fox.

“People have to find out what the government was doing during that period. If we’re worried about foreign influence, for the very same reason we should be worried about whether government officials abuse their power and put their thumb on the scale.”