Republican presidential candidate and former Florida Gov. Jeb Bush on Sunday discussed comments GOP rival Donald Trump made about his brother and former President George W. Bush.

And one point in the interview he asked, “Does anybody actually blame my brother for 9/11?”

Trump had implied in an interview Friday that he thought George W. Bush had some responsibility in the terrorist attacks Sept. 11.

“He was President,” Trump said. “Blame him, or don’t blame him, but he was President. The World Trade Center came down during his reign.”

Bush defended his brother on Twitter:

How pathetic for @realdonaldtrump to criticize the president for 9/11. We were attacked & my brother kept us safe. — Jeb Bush (@JebBush) October 16, 2015

Bush also responded to the comments on CNN’s “State of the Union” Sunday.

“Does anybody actually blame my brother for the attacks on 9/11? If they do they’re totally marginalizing our society,” Bush said. “It’s what he did afterwards that matters. And I’m proud of him and so are a bunch of other people. You don’t have to have your last name be Bush to understand that.”

“Next week Mr. Trump is probably going to say that FDR was around when Japan attacked Pearl Harbor,” Bush said.

CNN host Jake Tapper pressed Bush on how he could blame President Obama and former secretary of state and now Democratic presidential candidate Hillary Clinton for the attack on the Benghazi compound if he believed his brother was not at all responsible for 9/11.

“Well, I — the question on Benghazi, which we will now finally get the truth to, is was that — the place secure? They had a responsibility at the Department of State to have proper security.”

Trump tweeted about Bush Sunday morning:

Jeb Bush should stop trying to defend his brother and focus on his own shortcomings and how to fix them. Also, Rubio is hitting him hard! — Donald J. Trump (@realDonaldTrump) October 18, 2015

Bush continued to criticize Trump’s comments on foreign policy on CNN’s morning news program and mentioned the show Trump previously hosted, “The Apprentice.”

“Across the spectrum of foreign policy, Mr. Trump talks about things that as though he’s still on ‘The Apprentice.’ I mean literally talking about Syria saying ISIS should take out Assad then Russia should take out ISIS,” Bush said. “It’s though it was some kind of board game and not a serious approach. This is just another example of the lack of seriousness.”

This post has been updated.