The crowd at Thursday's Republican debate was not ready for introspection about the wars in Iraq and Afghanistan.

Fox News host and moderator Chris Wallace asked Florida Gov. Jeb Bush (R) to comment on the foreign policy legacy of his brother, former President George W. Bush.

"Given the fact that your brother got us into two wars in Iraq and Afghanistan that have still not ended," Wallace said, facing boos from the audience, "what lessons have you learned from his mistakes, sir?"

Bush said his foreign policy is driven by the "lessons of history," but he never specifically mentioned what happened during his brother's administration.

He said he believes Congress should have given President Barack Obama a new war authorization for the fight against the Islamic State group, although he said it should have been more open-ended than what Obama asked for.

"Because if we allow this to fester, we're going to have Islamic terrorism, multi-generations of this all across this country," he said. "The caliphate of ISIS has to be destroyed, which means we have to arm directly the Kurds, embed our troops with the Iraqi military, re-engage with the Sunni tribal leaders, get the lawyers off the damn backs of the military for once and for all, have a no-fly zone in Syria."

Soon after Bush entered the presidential race, he -- not surprisingly -- received questions about whether he would have invaded Iraq. The former governor stumbled and shifted his answer repeatedly, raising questions about whether he was really going to be as strong a candidate as many believed he would be.

Since then, he has largely embraced his brother's foreign policy legacy. When Donald Trump called the Iraq War a "disaster" in a September debate, Bush went after him.

"As it relates to my brother, there's one thing I know for sure: He kept us safe," Bush said. "I don't know if you remember, Donald -- you remember the rubble? You remember the firefighter with his arms around him? He sent a clear signal that the United States would be strong and fight Islamic terrorism, and he did keep us safe."

Bush was referring to an iconic 9/11 moment that happened on his brother's watch.

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