"This is troubling because we're at war," Bush said. "They declared war on us and we need to have a serious strategy to destroy ISIL, but the idea that that is a solution to this is just crazy. It makes no sense to suggest this," Bush said.
Bush attacked Trump for a claim he made that the United States should let Russia fight ISIL.
"He gets his foreign policy experience from the shows," Bush said. "That is not a serious kind of candidate. We need someone who thinks this through."
Trump, of course, did not want to back down, but he didn't attack Bush's positions, he attacked his personality per usual.
"We need toughness," Trump said. "Jeb Bush is a very nice person, but we need toughness."
At that point, Bush jumped in to stop Trump from disparaging him and began throwing out the dates Trump discounted ISIL.
"You said," Bush began. Trump jumped in "are you talking or am I talking?"
The exchange ended with Trump taking a final shot at Bush: "With Jeb's attitude we will never be great again."