Obama twice last year canceled visits to Australia, once to stay in town to lobby for passage of his health-care bill, and again in the wake of the oil spill in the Gulf of Mexico.

Australian ambassador to the U.S. Kim Beazley, said Obama’s mere appearance was “enormously important” to Australians. And for the U.S., Australia’s geographic location in the burgeoning Asia-Pacific region makes the longtime ally an increasingly important one as China’s might grows.

Although the US does not base forces in Australia it maintains a significant presence through the electronic spy base at Pine Gap, the Harold E. Holt submarine communications station in Western Australia and extensive exercising and training.

This includes the big Talisman Sabre programme that this year involved 22,500 US and Australian troops, 18 warships and 25 aircraft, training for American strategic bombers and strike jets, and frequent visits by US warships.

Obama and Gillard are expected to announce further moves likely to include even greater use of Australian facilities, embracing expanded rotations of US Marines through the Northern Territory and more visits by American ships and aircraft.

The moves would effectively counter an increasingly aggressive China, which claims dominion over vast areas of the Pacific that the U.S. considers international waters.

China has alarmed smaller Asian neighbors by reigniting old territorial disputes, including confrontations over the South China Sea.

Defense Secretary Leon Panetta has said the goal is to signal that the U.S. and Australia will stick together in face of any threats.

From Australia, Obama will head to Indonesia for a security summit with Asian nations before finishing his nine-day trip and returning to Washington on Nov. 20.