Trump, the flamboyant front-runner in the 15-candidate Republican field, once again provoked a tit-for-tat with Bush on Friday by saying his brother must share some of the blame for the attacks that occurred during his first year in office.
"Look, my brother responded to a crisis, and he did it as you would hope a president would do," Bush said on CNN's "State of the Union."
"The great majority of Americans believe that. And I don't know why he keeps bringing this up."
Bush said Trump's comments about the Sept. 11 attacks called his credibility into question. The former Florida governor attacked Trump's foreign policy credentials and compared his grip on international issues to a reality television show the billionaire businessman formerly hosted.
"Across the spectrum of foreign policy, Mr. Trump talks about things that -- as though he's still on 'The Apprentice,'" Bush said on CNN.
"Talking about Syria - saying ISIS should take out (Syrian President Bashar al-Assad), then Russia should take out ISIS, as though it was some kind of board game and not a serious approach," he said.
Trump doubled down on his comments during an appearance on "Fox News Sunday," using a oft-repeated Jeb Bush phrase - that his brother "kept us safe" - against him.
"Jeb said 'we were safe with my brother. We were safe.' Well the World Trade Center just fell down," Trump said on Fox.
"I'm not blaming George Bush, but I don't want Jeb Bush to say 'my brother kept us safe,' because September 11th was one of the worst days in the history of this country."
Bush has defended his brother's actions after the Sept. 11 attacks, but his campaign has kept its distance from the unpopular president indelibly linked to the unpopular Iraq war.
He mocked Trump's comments and likened them to blaming President Franklin D. Roosevelt for the World War Two attack on Pearl Harbor.
"Next week, Mr. Trump is probably going to say that FDR was around when Japan attacked Pearl Harbor," he said. "It's what you do after that matters. And that's the sign of leadership." — Reuters
