Trump's tweets were apparently prompted by Blumenthal's appearance on CNN's "New Day" Monday morning when he spoke to Brianna Keilar about several topics, including the Trump administration's pursuit of leaks, sanctions on North Korea and Justice Department special counsel Robert Mueller's ongoing investigation into Russia's interference in the 2016 election.
"Empaneling the grand jury shows that Bob Mueller is pursuing this potential wrongdoing by the Russians, the attack on our democracy, seriously and diligently -- and there is no minimizing or underestimating that attack by the Russians," Blumenthal said. "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. That investigation must be pursued."
Trump responded to Blumenthal's comments on Russia in a tweetstorm just minutes later.
"Interesting to watch Senator Richard Blumenthal of Connecticut talking about hoax Russian collusion when he was a phony Vietnam con artist!"
"Never in U.S.history has anyone lied or defrauded voters like Senator Richard Blumenthal. He told stories about his Vietnam battles and...." he wrote in a second tweet.
He continued: "...conquests, how brave he was, and it was all a lie. He cried like a baby and begged for forgiveness like a child. Now he judges collusion?"
Later in the afternoon, Trump tweeted:
Blumenthal responded to Trump's comments less than two hours later, directly addressing and chiding the President's behavior in his own series of tweets.
"Mr. President: Your bullying hasn't worked before and it won't work now. No one is above the law."
He continued: "This issue isn't about me - it's about the Special Counsel's independence and integrity."
This isn't the first time Trump has lashed out against Blumenthal, specifically regarding his military service. Trump made similar comments back in May after Blumenthal called the President's decision to fire former FBI Director James Comey "a looming constitutional crisis." Trump also tweeted about Blumenthal's military service in February during the confirmation process for now-Supreme Court Justice Neil Gorsuch.
Trump's digs are a reference to Blumenthal's past misrepresentations about his service during the Vietnam era. The senator admitted in 2010 to misrepresenting his military service after saying he had been "in" Vietnam. Blumenthal served in the Marine reserves in Washington, not Vietnam, during the war.
"I have misspoken about my service, and I regret that, and I take full responsibility," Blumenthal said in 2010.
While Blumenthal enlisted in the Marine Reserve after multiple deferments, Trump -- who was also eligible for the draft during the Vietnam War -- never enlisted, instead obtaining multiple student deferments and ultimately a medical deferment for a bone spur to avoid the military draft.