Australian Prime Minister John Howard has arrived in Japan on a visit which will include the signing of a bilateral security pact.
Mr Howard will hold talks with Japanese Prime Minister Shinzo Abe
The declaration is thought to include co-operation on terrorism, peacekeeping and disaster relief.
The government has dismissed suggestions that the defence deal could strain ties with China.
Meanwhile, Australian diplomats are due in North Korea for talks on its nuclear programme.
The delegation will urge Pyongyang to abide by its agreement last month to start dismantling its nuclear facilities.
Such progress could result in Australian aid, a spokeswoman for Australia's Department of Foreign Affairs and Trade told local media.
'Not directed at China'
During the four-day visit to Japan, Mr Howard will hold talks with Japanese Prime Minister Shinzo Abe.
The two are scheduled to sign the security declaration on Tuesday, the Japanese Foreign Ministry said.
Full details of the pact have not been revealed but observers say it will include intelligence sharing and possible joint exercises.
And in an interview with Japanese daily the Yomiuri Shimbun, Foreign Minister Alexander Downer said it was expected to include a pledge to co-operate against the threat of proliferation from North Korea.
The Australian government has played down concern that strengthening security ties with Japan could affect relations with China.
"This isn't directed at China, it needs to be looked at in the context of our bilateral relationship with Japan," Mr Downer told local media.
Correspondents say Australia has been looking to exert more influence in Asia, in terms of business as well as regional security.
Talks on a free trade agreement between Japan and Australia are due to start next month.
And Tokyo is also keen to pursue closer alliances with countries in the region including Australia and India.
This will be Japan's second bilateral security deal - its other one is the Japan-US Security Treaty which dates from 1960.