He concluded by further distancing himself from the meeting his son arranged, writing: "I did not know about it!"
Trump was responding to a Washington Post report this weekend that although he does not think his eldest son intentionally broke the law, he is worried that Trump Jr. may have unintentionally stumbled into legal jeopardy and is embroiled in Mueller's investigation largely because of his connection to the president.
The Trump Tower meeting also included Trump's son-in-law, Jared Kushner, and his campaign chairman at the time, Paul Manafort, who is on trial over tax and bank fraud charges after being indicted by Mueller.
Trump's tweet, however, conflicts with a statement that Trump Jr. had released to The New York Times in July 2017, as the newspaper prepared to report about the meeting. In that statement, Trump Jr. had indicated that the meeting had been "primarily" about the issue of the adoption of Russian children by Americans.
Amid public uproar over the meeting, the president's son was forced to release follow-up statements, ultimately acknowledging that the meeting's true purpose had been to get dirt about Hillary Clinton from a lawyer he had been told was working for the Russian government.
The Washington Post reported a few weeks later that Trump Jr.'s initial misleading statement had been "dictated" by Trump.
The president's attorneys at first denied that Trump's involvement in drafting the response to the Times, but months later, in a letter intended to explain why Mueller should not interview Trump, they agreed that the president had, in fact, authored the statement. They described the statement, which had not mentioned that the Russian lawyer was expected to bring damaging information about Clinton, as "short but accurate."
And they said that Trump Jr., Kushner and White House staff had made a "full disclosure" about that session to Mueller and Congress.
Trump Jr.'s testimony to Congress contained a similar defense as his father's Sunday tweet, indicating that he saw no reason not to accept a meeting that could yield important information about Clinton, even though he was told that it was part of an effort by the government of a hostile power.
In addition to weighing in publicly on the Trump Tower meeting, the president also unleashed angry tweets against the media Sunday morning from his 11-day working vacation in nearby Bedminster.
In one tweet, he declared the media the "Enemy of the People" and accused them of sowing division and distrust. "They can also cause War!" Trump wrote. "They are very dangerous & sick!"
In another, he expressed frustration with both the media and Mueller's probe. "Too bad a large portion of the Media refuses to report the lies and corruption having to do with the Rigged Witch Hunt - but that is why we call them FAKE NEWS!"