
Bush told CBS television's Face the Nation on Sunday morning the 2003 invasion he ordered was the "right decision."
But the 68-year-old added: "My regret is that a violent group of people have risen up again.
"This is al-Qaida plus ... they need to be defeated. And I hope we do (...) I hope that the strategy works."
On Saturday, U.S. warplanes launched airstrikes on a gathering of IS leaders in northern Iraq. The commander of IS, Abu Bakr al Baghdadi, was wounded, Iraqi officials said.
In the wide-ranging interview, Bush also said his younger brother Jeb Bush, a former Florida governor, was "wrestling with the decision" of whether to run for the White House in 2016.
He said: "I think it's 50-50."
"He knows exactly, you know, the ramifications on family, for example," Bush added. "He's seen his dad and his brother go through the presidency. I'd give it a tossup."
By Ruchi Singh
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