Los Angeles: Republican White House pick John McCain broke with President George W Bush on glaring disputes that soured relations with US allies, but said America had a moral duty to stay in Iraq.

The Arizona senator grabbed the spotlight as the Democratic race between Hillary Clinton and Barack Obama took another negative lurch, while the former first lady vowed to fight on all the way to the party's August convention.

"Our great power does not mean we can do whatever we want, whenever we want, nor should we assume we have all the wisdom and knowledge necessary to succeed," McCain said yesterday in a major foreign policy address here.

The Arizona senator heralded a hawkish approach to what he said was the "transcendent challenge of our time - the threat of radical Islamic terrorism," and mooted a robust defence of US interests against Russia and China.

McCain related his family's military heritage to frame his world-view as a "realistic idealist" and, in an apparent shot at Obama, warned "we cannot wish the world to be a better place than it is."

"I detest war. It might be the worst thing to befall human beings, but it is wretched beyond all description," the former Vietnam prisoner of war said.

"Whatever gains are secured, it is loss the veteran remembers. Only a fool or a fraud sentimentalises the merciless reality of war," he told the Los Angeles World Affairs Council.

McCain carved out clear differences with Obama and Clinton, who have both vowed to end the unpopular Iraq war and bring US troops home if elected president in November.

Source : PTI