Our army, now configured for ground fighting in distant places, such as the Middle East, has next to no relevance to our immediate strategic problem, the threat from China. But it is the right service to take on a new capability that would be highly relevant: long-range missile strike.

Radically adapting the army for this should be a key recommendation from a review of defence policy due for completion in March.

Long-range strike capability strongly deters war - or helps win if deterrence fails. An enemy facing it must worry about not just its forces at the front but about immobile things it needs in the rear, especially bases.

For Australia, long-range strike has been a role for the air force - specifically its strike wing, which has Super Hornet fighters, and the tanker squadron that extends their reach.

Strike missiles are large and expensive weapons that do the same job when targets are too heavily defended or too distant for attack by aircraft. Long-range anti-ship missiles are physically similar, and can in fact also be strike missiles, capable of hitting ground targets, too.

Defending against strike or anti-ship missiles costs more than the weapons themselves.

So China has an entire military service, called a rocket force, that's devoted to firing strike and anti-ship missiles from land. It uses launcher vehicles that are much cheaper than aircraft and ships, can keep moving between hiding places and are therefore hard to find and destroy.

This is a big part of the strategy that Beijing is using to ward off the US Navy and Air Force, making the Western Pacific increasingly unstable. In a war, foreign bases 3000 kilometres from China would be at great risk from these weapons; ships approaching China would be in danger, too.

We need a similar capability - but not a new military service like the rocket force. This should be a job for our army.

More specifically, a new army organisation equipped with strike and anti-ship missiles, which we might call the Strike Brigade, should be set up in the army reserve.

Our army reserve is flexible, full of talented people and spread around the country - as our strike missiles should be, to reduce their vulnerability. Also, operating such push-button equipment does not require the level of physical fitness and combat skills that are more associated with the regular (full-time) army.

Forget the Middle East. These days Australia has to consider two main military tasks on its own side of the world.

The immediate one is supporting the US in deterring an attack on Taiwan, a maritime and air mission in which our army's only role would be guarding Top End bases.

So we should redirect $40 billion that has been earmarked for modernising the army. Use some of the money to create the Strike Brigade.

If China set up bases in the Solomons, Papua New Guinea or East Timor, as it no doubt would like to do, and if war broke out despite every effort at deterrence, the Strike Brigade would strongly help the air force in dealing with those installations.

If countries to our north allowed territorial access, the Strike Brigade could move forward to more directly support Taiwan, especially by targeting ships. Since such possibilities would become part of China's calculation of risk before deciding to attack Taiwan, they would reduce the chance of war.

The second military task that we have to consider is more distant, and even more disturbing: if China took Taiwan, and if overawed East Asian countries became its vassals, it would probably be able to build up powerful forces on our doorstep. Indeed, we would have to seriously protect ourselves against invasion - not because landings would be likely but because an irresistible threat of them could well force Australia also to become an obedient servant of the Chinese Communist Party.

But a Strike Brigade would deter approaches to our shores in the same way that China's rocket force now presents a challenge to the US.

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In those circumstances the traditional capability of the army would also be needed - in Australia. So we should keep all the army's three combat brigades; they'd be the basis of a ground force we'd need to expand rapidly.

Such a desperate situation probably could not arise until well into the 2030s, however. That's why the currently planned modernisation the ground combat force can be safely suspended.

Also, we must absorb lessons from the war in Ukraine before plunging into re-equipping the army for ground fighting.

Our army is already planning to buy surface-attack missiles that fly tens of kilometres, like those that Ukraine is launching against Russian ammunition dumps just behind the front line. But these would be weapons for ground battles.

We need ground-launched strike and anti-ship missiles that would fly much farther.

Conveniently, the US Army is right now stepping up to the same mission, having been kept out of it for decades by a now defunct treaty with Russia. It's starting by adopting two missile types from the US Navy, the Tomahawk and SM-6.

We're buying Tomahawks and SM-6s for our navy, too.

That makes things straightforward. Our army just needs to tag along behind the US Army in creating a strike-missile capability. Defence Minister Richard Marles should pre-empt the defence review by launching preparations now.