Announcing the government's new national security strategy, Ms Gillard said Australia would boost its diplomatic representation in the Asia-Pacific region in an effort to promote stability as the region undergoes dramatic change.

And the government would establish an Australian Cyber Security Centre, which will strengthen the digital defences of key departments and work with businesses to ensure their systems are well protected.

Ms Gillard said the behaviour of countries would once again dominate Australia's national security thinking, ending an era in which ''non-state actors'', such as terrorist groups, posed the greatest risk.

''The 9/11 decade is ending and a new one is taking its place,'' Ms Gillard said.

Rising incomes in Asia meant governments were spending more on defence forces. Equally, population growth and affluence were putting pressure on energy, water and food resources, Ms Gillard said - pointing to the risk that well-armed nations may fight over resources in the future.

Countries including China, Indonesia, Vietnam, Thailand and Cambodia are increasing their defence spending and modernising their militaries in what, some experts say, verges on an arms race. Territorial disputes, particularly in the South China Sea, are causing tensions.

The new strategy has received mixed reactions from security experts. Australian Strategic Policy Institute executive director Peter Jennings said it was ''one part common sense and one part disappointment'', in that it did not spell out how the government would meet broad aspirations in an era of belt tightening.

''Notwithstanding the language, the government's cuts to national security spending actually demonstrate that, for them, this is a lower priority.''

Ms Gillard will on Thursday announce further details on the Cyber Security Centre, which will bring together Defence, ASIO, the Australian Federal Police and the Australian Crime Commission.

Gary Waters, a cyber security expert from Kokoda Foundation, welcomed the fact that the digital threat was becoming part of every security discussion.

''They've sought to normalise cyber within the national security contract, rather than present it as something in itself,'' he said.

Peter Leahy, former Chief of the Army, now director of the University of Canberra's National Security Institute, said the strategy was ''a really good start''.

But on cyber security, the threat was ''of such a magnitude'' that a separate agency should be created to deal with it, he said. And the Department of Foreign Affairs was underfunded for the extra diplomatic work Ms Gillard promised.

Professor Leahy also questioned Ms Gillard's declaration that the 9/11 decade was over.

''I fear that in future years we might just be talking about the 9/11 century,'' he said.

Australian National University professor of national security Michael Wesley agreed, saying Ms Gillard had made ''a big call''.