President Donald Trump teed off on one of his favorite Senate targets Monday morning, calling Sen. Richard Blumenthal “a phony Vietnam con artist” whose past misstatements about his military service should disqualify him from commenting on the ongoing Russia investigations.

“Interesting to watch Senator Richard Blumenthal of Connecticut talking about hoax Russian collusion when he was a phony Vietnam con artist!” Trump wrote on Twitter Monday morning.

“Never in U.S. history has anyone lied or defrauded voters like Senator Richard Blumenthal. He told stories about his Vietnam battles and conquests, how brave he was, and it was all a lie,” Trump wrote in a pair of subsequent posts. “He cried like a baby and begged for forgiveness like a child. Now he judges collusion?”

Blumenthal (D-Conn.) had appeared on CNN’s “New Day” minutes before Trump began his online critique of the lawmaker, telling anchor Alisyn Camerota that “there is no minimizing or underestimating that attack by the Russians” on the U.S. presidential election last year.

“It was purposeful and relentless, and it involved propaganda and hacking into our voting machines or at least an attempt to do it and potential collusion by the Trump campaign and then obstruction of justice,” he said.

The president’s attack against Blumenthal’s military record dates back to a controversy from the Connecticut senator’s 2010 campaign, when he held a press conference to explain that while he had repeatedly stated that he served “in” the Vietnam War, he had in fact only served during the war. Blumenthal was in the Marine Corps Reserves for six years during the Vietnam War and did not serve overseas during that time.

The president, who received five draft deferments during the Vietnam War for educational purposes and bone spurs in his heels, has previously called Blumenthal’s misstatements about his military service a “major lie.”

A spokeswoman for Blumenthal did not immediately return a request for comment.

Trump, others in his administration and outside allies have all repeatedly and emphatically denied that there was any collusion between the Russian government and the president’s campaign, an allegation that is part of separate ongoing investigations by the House and Senate intelligence committees as well as one led by special prosecutor Robert Mueller.

Diamond Naga Siu contributed to this report.