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SIMI VALLEY, California - Australian Foreign Minister Alexander Downer has come to the defence of US President George W Bush, describing him as "a person of enormous courage".

Downer's support came just days after former US President Jimmy Carter described the Bush administration as the "worst in history" for its impact around the world.

Downer, speaking alongside US Secretary of State Condoleezza Rice at the Ronald Reagan Presidential Library, located on the north-west outskirts of Los Angeles, compared Bush's war on terror to Reagan's Cold War victory over the Soviet Union.

"When I think about the war on terror and the decisions he has had to make, these have been tough decisions," Downer told about 300 guests, including Reagan's widow, Nancy.

"The final judgments about his presidency in relation to some of those decisions will be made years and years off into the future.

"... Will people say of President George W Bush that he ran away when the terrorists struck?"

"I don't they will say that about him either. They will say that he confronted them and showed a lot of courage in doing so."

Downer will spend today and tomorrow with Rice in California, with a tour of the Camp Pendleton military base, south of LA, and visits to technology sites near San Francisco.

- AAP