Donald Trump isn't talking much to reporters this weekend, but he still has a lot to say to Jeb Bush, as the two presidential contenders engaged in a back-and-forth public argument about 9/11 terrorist attacks, according to CNN.

The attacks on Sept. 11 have been mentioned several times in the Republican primary campaign because Jeb Bush is the younger brother to former President George W. Bush. Trump brought this to the forefront again Friday while speaking on Bloomberg TV. "When you talk about George Bush, I mean, say what you want, the World Trade Center came down during his time," he said.

Jeb Bush responded on Twitter by saying Trump's comments were "pathetic."

"Your brother's administration gave us Barack Obama, because it was such a disaster, those last three months, that Abraham Lincoln couldn't have been elected," Trump said to Bush during the second Republican debate, according to The New York Times.

Trump fired back at Jeb Bush on Twitter, calling him "pathetic" as well, according to Yahoo! News. "No @JebBush, you're pathetic for saying nothing happened during your brother's term when the World Trade Center was attacked and came down."