Donald Trump and Jeb Bush took their latest dust-up — this one over President George W. Bush and the 9/11 terrorist attacks — to the Sunday morning talk show circuit, saying it reflects fundamental differences over foreign policy.

Trump told Fox News Sunday he doesn’t blame George W. Bush for the attacks of Sept. 11, 2001, but does question Jeb Bush’s claim that his presidential brother kept the nation “safe” — using 9/11 as the prime example.

“Look, look, Jeb said we were safe with my brother — we were safe,” the Republican front-runner told Fox. “Well, the World Trade Center just fell down! Now, am I trying to blame him? I’m not blaming anybody. But the World Trade Center came down.”

Bush, who has called Trump’s comments “pathetic,” told CNN’s State of the Union: “Look, my brother responded to a crisis, and he did it as you hope a president would do.”

The former Florida governor — who has fallen far behind Trump in GOP presidential polls — said his brother united the country after 9/11, organized a response to the attack, and “he kept us safe.”

Bush told CNN that Trump’s response shows a fundamental lack of seriousness about foreign policy, whether it’s terrorism or the current conflict in Syria.

“Across the spectrum of foreign policy, Mr. Trump talks about things as though he’s still on ‘The Apprentice,’” Bush said, referring to the businessman’s television series.

Trump, who first made his 9/11 comments in an interview with Bloomberg Television, toldFox News Sunday that his immigration policy could have blocked the 2001 attacks because “I doubt that those people would have been in the country” in the first place.

“With that being said, I’m not blaming George Bush,” Trump said. “But I don’t want Jeb Bush to say my brother kept us safe because September 11 was one of the worst days in the history of this country.”