Charleston (USA): US President George W Bush defended the war in Iraq as "an act of justice" and said he had no regrets despite the failure so far to find weapons of mass destruction (WMDs) there.

"Knowing what I knew then, and knowing what I know today, America did the right thing in Iraq," Bush said in an impassioned defense of the invasion during a brief trip to Charleston to tout his record on national security.

The mounting death toll among US troops in Iraq, resistance to the US-backed plan for the transfer to self-rule, and the failure to find the banned arms at the core of his case for war pose an election-year threat to Bush.

Bush, who has dropped his ironclad pre-war assertions that Saddam Hussein had chemical and biological arms and sought nuclear weapons, now says the ousted Iraqi dictator had posed "a gathering threat".

"We know Saddam Hussein had the intent to arm his regime with weapons of mass destruction," he insisted as he sought to banish Democrats' criticisms from voters' minds.

"The liberation of Iraq was an act of justice, delivering an oppressed people from an evil regime. The liberation of Iraq removed a source of violence and instability from the Middle East. And the liberation of Iraq removed an enemy of this country and made America more secure," he said.