President Trump suggested Sen. Richard Blumenthal, D-Conn., take a "nice long vacation in Vietnam" after the Democratic senator accused the president of trying to politicize the Justice Department.

"I think Senator Blumenthal should take a nice long vacation in Vietnam, where he lied about his service, so he can at least say he was there," Trump said on Twitter on Monday afternoon.

The president's tweet is the latest in a back-and-forth that both Trump and Blumenthal have engaged in since Monday morning.

The Connecticut Democrat appeared on CNN early Monday morning and said an announcement from the Justice Department on Friday that it's reviewing its subpoena policies for reporters was part of Trump's attempts to "politicize" the agency.

Blumenthal said the announcement would have a "chilling effect on the press and on whistleblowers" and credited the media for publishing information about meetings members of Trump's team held with Russian officials.

After Blumenthal's appearance, Trump fired off a several tweets criticizing the Connecticut senator for saying he served in Vietnam when, in fact, he never did. Instead, Blumenthal received five military deferments.

"Interesting to watch Senator Richard Blumenthal of Connecticut talking about hoax Russian collusion when he was a phony Vietnam con artist!" Trump tweeted. "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."

"He cried like a baby and begged for forgiveness like a child," the president continued. "Now he judges collusion?"

In response to Trump's tweets, Blumenthal took to his own Twitter account to accuse the president of trying to bully him.

"Mr. President: Your bullying hasn't worked before and it won't work now. No one is above the law," Blumenthal tweeted Monday morning. "This issue isn't about me — it's about the Special Counsel's independence and integrity."