The United States fully supports a proposed trilateral security dialogue with Japan and Australia, U.S. Deputy Secretary of State Richard Armitage said Friday.

Armitage said a "more robust relationship" between the three states would build on existing bilateral ties.

"I've noted that Australia has a very close -- primarily political and economic -- relationship with Japan. The United States has a very close economic and political, military and security relationship with Japan," he told reporters in Sydney.

"It seems to me we are all democracies, we're all concerned with the fate of Asia and it seems to me a perfectly reasonable proposition that we ought to get together and talk . . . the United States is 100 percent willing to take part," Armitage said.

Details of the proposed dialogue emerged following defense talks between Australia and the U.S. in late July.

The key objective of the U.S. in its relationship with Japan is ongoing cooperation in the bilateral alliance, the cornerstone of the U.S. security presence in the Asia-Pacific, Armitage said.

The U.S. would support Prime Minister Junichiro Koizumi's "monumental task" of structural reform in Japan and hoped to see Japan take a more proactive security role in terms of regional peacekeeping, he said.

"We're very interested that Japan take an appropriate role in peacekeeping endeavors and to that end we would be encouraging Japan to take a more robust role."

Armitage will meet Prime Minister John Howard on Saturday ahead of Howard's visit to the U.S. next month.