Hybrid warfare, for those unfamiliar with the term, is a military strategy that blends conventional warfare, irregular warfare and cyberwarfare with other influencing methods, such as fake news, use of social media, diplomacy, electoral intervention, and "lawfare" to pursue a nation's political ends. (Lawfare is the use of a legal system against enemies to damage or de-legitimise them, tie up their decision-making processes, or win a public relations victory.)

There will always be a place for the use of military force, but a hybrid approach aims to undermine and defeat an adversary by fusing a range of offensive and opinion-shaping options. The intention is to leave the population of the adversary (and observer nations) confused or ambiguous as to the legitimacy of their position. When Western populations distrust their own politicians - as is often the case - this task is made easier.

This means for Australia that we need to re-examine how we approach defence. Big dollar spending on ships and aircraft of the kind advocated by conservative military planners - and endorsed by successive Australian governments wanting to look serious about "national security" - may not be the best use of limited national resources.

Nations need to have clear strategic aims. Both Russia and China know what they want in the Middle East and South China Sea respectively, while the West and Australia just tend to muddle along - as we have in Afghanistan - which puts us in a disadvantageous reactionary position.

I have just been at a conference at Cambridge, England, where NATO's European concerns were discussed. NATO has traditionally viewed threats as being solely related to military capability and intent. This rigid military approach ignores the fact that hybrid warfare does not rely on military capability to change the political landscape.

For example, Russia's occupation of Crimea in 2014 did not employ the might of the Russian Army, rather it utilised a combination of special forces, local insurgents acting as a fifth column, "volunteer" mercenaries, and supportive propaganda. The takeover was then legitimised by a referendum of Crimean residents, 96.7 percent of whom voted to leave Ukraine and join the Russian Federation. (Ukraine had not endeared itself to Crimea residents by its inept and corrupt handling of the Sevastopol Naval Base lease negotiations.)

Russia, with a GDP comparable in size to Australia's, cannot afford to engage in an arms race with the US, so in chess-like fashion it has embraced the concept of "non-linear" warfare, which is the deployment of "conventional and irregular military forces in conjunction with psychological, economic, political, and cyber assaults" to achieve its political aims.

Israel is another country that has adopted this approach to counter its enemies.

The employment of "hard power" - that is the use of conventional military force - to achieve a political aim or counter a hybrid threat may not be effective, and can even make the user look like a bully to the international community. That's an ongoing problem faced by the US as the sole superpower.

In recognition of the new strategic challenges, the UK is forming an army division specialising in hybrid warfare to better prepare the British military for 21st Century conflicts. The new division will focus on intelligence gathering, cyber operations, counter-propaganda, and electronic warfare.

A parallel problem for Western military forces is that major weapons platforms, such as ships and aircraft, are becoming more vulnerable for a range of reasons. These include the adoption by potential adversaries (such as Russia and China) of less expensive counter-options - like hypersonic missiles against which surface ships have no defence, and the development of unmanned aerial and underwater platforms that will outperform manned ones.

"Boots on the ground" was the ultimate way of finalising a conflict but can be less effective now - US-led coalition operations in Iraq and Syria being recent examples. We are now up against adversaries who can put far more boots on the ground than we can, are less concerned about casualties, or who can engage in protracted long-term resistance - as in Afghanistan - to wear down our domestic support for overseas operations.

As Clausewitz observed: "A fast moving environment can evolve more quickly than a complex plan can be adapted to it. By the time you have adapted, the target has changed." In Australia's case, the changing nature of warfare suggests a greatly increased role for flexible special forces, counter-narratives, psychological and cyber warfare - and perhaps less emphasis on traditional defence structures.