Sarah Palin defended herself against charges of inexperience on Thursday, insisting she is ready to serve America as vice-president - but then appeared to be ignorant of the "Bush doctrine" which has defined much of American national security policy in recent years.

Before exposing herself to tough questions for the first time since becoming John McCain's surprise pick as Republican running mate two weeks ago, the Alaskan Governor had spent several days preparing for her TV interview.

As expected, she was cross-examined vigorously on foreign affairs, telling ABC News that countries like the Ukraine and Georgia should be admitted to Nato - a policy enthusiastically advocated by Mr McCain.

Asked if that meant America should go to war with Russia if Georgia was attacked again, she replied: "Perhaps so. I mean, that is the agreement when you are a Nato ally is if another country is attacked, you’re going to be expected to be called upon and help."

Last month, during Russia's military incursion into Georgia, Mr McCain made plain that he did not favour US personnel getting involved in the conflict.

On the day that America commemorated the September 11 terrorist attacks, her worst moment came when she was flummoxed by a question about whether she supported a policy the president had developed to snuff out future threats.

"Do you agree with the Bush Doctrine?" she was asked. "In what respect," she replied, "his worldview?"

"No, the Bush Doctrine," said the interviewer, "enunciated September 2002, before the Iraq War."

Mrs Palin then gave a long and possibly prepared answer which underlined the McCain campaign's efforts to distance itself from the current administration.

“What President Bush has attempted to do is rid this world of Islamic extremism, terrorists who are hell-bent on destroying our nation,” she said. “There have been blunders along the way, though, there have been mistakes made."

It was then explained that the doctrine was one of "anticipatory self-defence,” - or pre-emptive strikes against perceived threats. But she hesitated about backing a policy favoured even by Barack Obama of making cross-border attacks on al-Qaeda bases in Pakistan. Eventually, she declared: "I believe that America has to exercise all options in order to stop the terrorists who are hell-bent on destroying America and our allies. We have got to have all options out there on the table.”

Had she ever travelled outside the United States? Yes, she said, to Canada, Mexico and Kuwait - where she visited Alaskan soldiers. Had she ever met a foreign head of state? “I have not,” she admitted before stating that one of the points of running as an outsider was she did not have a "big fat resume that shows decades and decades in that Washington establishment".

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