Donald Trump. REUTERS/Randall Hill Republican presidential frontrunner Donald Trump on Thursday defended his criticism of former President George W. Bush's handling of the Iraq war.

During a CNN town-hall event Thursday, Trump appeared to walk back his earlier assertion that the Bush administration lied about the existence of weapons of mass destruction in Iraq. He sidestepped the question when a voter asked him to clarify how Bush lied.

"I don't know. Whether he lied or not, it was a terrible decision," Trump said.

When pressed by CNN host Anderson Cooper several minutes later, Trump hypothesized that there may be other reasons Bush decided to invade Iraq. Trump suggested those included Bush's loyalty to his father, former President George H.W. Bush, who deployed US troops to fight former Iraqi dictator Saddam Hussein during the Gulf War.

"I'd have to see the exact wording. Look, I don't know. I'd say that something is going on," Trump said. "I will say I don't know why he went in. Honestly, there was no reason to go in."

During the Thursday town hall, the mogul faced increasing scrutiny over his position on the war in Iraq.

Trump was also asked about a 2002 interview on Howard Stern's radio show, newly reported by BuzzFeed on Thursday, during which he said he tepidly supported the invasion. Trump shrugged off Cooper's question about his past remarks, saying he didn't remember the interview.

"By the time the war started, I was against the war," Trump said.

He added: "I don't remember that, but it was probably the first time I was ever asked about the war."