Republican presidential candidate Donald Trump said that he doesn't blame former President George W. Bush for the 9/11 attacks, but was still highly critical of the former president's decision to pursue the war in Iraq.

During Saturday night's GOP debate, Trump was asked whether he stood by a 2008 interview where he said it would have "been a wonderful thing" if Democratic leader Nancy Pelosi had tried to impeach Bush for starting the war. Amid Trump's criticism, his fellow presidential candidate, Jeb Bush, said he was "sick and tired of [Trump] going after my family."

As Bush defended his brother's ability to keep the nation safe, Trump said, "The World Trade Center came down."

In an interview with "Face the Nation" after the debate, Trump said, "I am not blaming [President Bush], although...the CIA said there was a lot of information that something like that was going to happen. I'm not blaming anybody. It's a tragedy." He called it "worse than Pearl Harbor because you're talking about civilians.

"Now, could he have done something about it? His CIA knew about things happening... but when Jeb gets up and says, we were safe under his brother, we weren't safe," Trump added.

He also said "I'm not blaming anybody" for saying there were weapons of mass destruction in Iraq, which turned out to be false.

"I'm just saying he went in there, he thought there were weapons of mass destruction, maybe or maybe he didn't," Trump said. "If he knew that there weren't weapons of mass destruction and if he used that as an excuse to go in and try to make up for some sins for previous years then it would be a lie."

He was still harsh about Bush's decision to push for the war in Iraq, saying it was a "disaster" that may lead to "the destruction of Europe" because of migrants fleeing the region.

"We would have been so much better off if Bush and the rest of them went to the beach and didn't do anything. If you had Saddam Hussein, he was a bad guy and all of that, but he made a living off killing terrorists. Now if you want to become a terrorist you go to Iraq. That's like the Harvard of terrorism," he said.

Trump said he believes Saturday's debate "might have been my best performance." He tangled with multiple opponents but also sought to dispel the notion that he might be moderating his behavior at all.

"Look, I went to an Ivy League school. I know how to behave. I could be so politically correct you would be just bored to tears," he said. On his pledge to cut his use of profanity he said, "I've always done it just as a way of emphasis and had fun doing it. But running in politics we can't do it."

But a minute later he concluded that some profanity here and there was, "Ehhh...not a big deal."

As he tries to sustain his momentum from his first-place finish in New Hampshire, Trump said his campaign is "doing great" in South Carolina. He said he doesn't want to use robo-calls as a campaign technique, and bemoaned the state of politics these days.

"I deal with Manhattan real estate, these people are babies compared to the politicians," he said.

He pledged to release his tax returns sometime in the next three or four months. When Dickerson noted that might be after the nomination is sewn up, he brushed it off.

"I don't know, I'll do them as soon - Look, I'm the first one to put my financial statement out," Trump said. "But I have one of the world's most complicated tax returns. It's a massive return, but I will get it done as soon as I can."