President Trump slammed former President George W. Bush over the 2003 U.S. invasion of Iraq - referring to it as "the single worst decision ever made," and that it was comparable to "throwing a big fat brick into a hornet's nest."

Speaking to a group of GOP donors at a Mar-a-Lago closed door lunch and fundraiser, Trump also mocked Bush's intellect: "Here we are, like the dummies of the world, because we had bad politicians running our country for a long time," reported CNN - which obtained leaked audio from the event.

"That was Bush. Another real genius. That was Bush," Trump joked. "That turned out to be wonderful intelligence. Great intelligence agency there."

In the past, Trump has been notoriously critical of the decision to invade Iraq, slamming Jeb Bush during the 2016 primaries over his brother's decision to invade.

Jeb, why did your brother attack and destabalize the Middle East by attacking Iraq when there were no weapons of mass destruction? Bad info? — Donald J. Trump (@realDonaldTrump) October 18, 2015

"@FlightAJ: Hey @realDonaldTrump what is your view on George Bush?" He got us into Iraq instead of making America great again. Not good! — Donald J. Trump (@realDonaldTrump) June 17, 2014

We spent TWO TRILLION DOLLARS in Iraq and got NOTHING. Now we are going back and will again get NOTHING because our leaders are clueless! — Donald J. Trump (@realDonaldTrump) November 8, 2014

Bush snarks back

Former President Bush - despite rarely criticizing President Obama - only took a month into Trump's presidency to begin tossing barbs. Following Trump's controversial Executive Order banning travel from several countries associated with terrorism, Bush 43 said: "I don’t like the racism and I don’t like the name-calling and I don’t like the people feeling alienated. Nobody likes that."

Last October, Bush indirectly slammed Trump at a policy seminar in New York - telling the audience “We have seen our discourse degraded by casual cruelty... We’ve seen nationalism distorted into nativism.”

“Bullying and prejudice in our public life sets a national tone, provides permission for cruelty and bigotry, and compromises the moral education of children,” said Bush. “The only way to pass along civic values is to first live up to them.”

Trump and the Bush family have had a good relationship - as neither George W. Bush, his father former President George H.W. Bush, or Jeb Bush endorsed him during the 2016 election.