China could not ramp up steel production because it imports the raw materials from far away, mostly from Australia. Most of the raw materials, including energy and even food are imported into China. None of those supply chains would be left untouched in a war.
China is food-safe in calories. Not in dollars, because China produces less expensive food than they import.
While yes the raw materials are currently imported from Australia, in war-time they would be imported from Russia and Central Asia. Preparations are being made right now to facilitate this.
China is also #4 in iron ore reserves, they just aren't as economical as Australia's. Of course that doesn't matter much in wartime.
And the first thing the US should do in the case of a large scale war involving China, is hand Australia nuclear weapons for its self-defense. It would guarantee an extraordinary cost if China were to decide to destroy Australia to try to annex their land for resource extraction. In the coming decades China will have the military capability to invade Australia, given China's rapid naval expansion. It's not a sure thing that the US could stop them. If China is cut off from their required resources, they'll invade somewhere as a response. Australia needs a plan for if all else fails, an ultimate deterrence to invasion (which France and Britain possess for similar deterrence reasons).
It's not an ultimate deterrence to invasion. MAD is a theory, not an iron law of the function of the universe. If there's one thing World War II taught us, it's quite possible for modern life to continue despite 8 figure casualties, and quite possible for industrial output to increase even under the most severe conditions.
Australia is hard to invade because it's a separate continent, not solely because it would be protected by nuclear weapons. It's all the other normal stuff related to the challenge of conducting opposed landings over long distances that would make it very costly to attack. The nukes are a plus but they are not magical. All modern nations have tons of expendable population. It's politically convenient to present nukes as the ultimate deterrent but it's not backed by empirical evidence. The other issue is that due to test ban treaties we really do not know how currently existing stockpiles of such weapons will perform under real conditions. We could have vast stockpiles of antiquated garbage. We just don't know.
Throughout all of recorded history there has yet to be a superpower or empire that didn't do incredibly stupid things, courtesy of over-estimating its position and power. Modern China will not be an exception. They'll overreach repeatedly just as every other prior great power has.
China considers Australia to be within its primary sphere of influence (a rapidly expanding sphere as far as China is concerned, as they push outward militarily).
Japan was willing to invade Indonesia, Malaysia, Papua New Guinea and Australia during its Empire days. China is a drastically more potent superpower than the Empire of Japan ever was and China's military reach will be far greater.
In an Asia war scenario (which is what we're talking about here), Australia is absolutely on the table to be invaded by China. It's a prime candidate if China's foes attempt an inevitable resource blockade (which would see the BRI targeted early on). Invading Australia also disables a critical, reliable ally for the US side. The US & Co. would need vast regional resource supplies to sustain for long at all in a conflict with China in Asia; China would know that, and would understand that Australia is one of the most important resource suppliers both regionally and globally. At a minimum China would seek to cripple Australia functionally, and an invasion is ideal toward that ultimately (otherwise the Australians would just keep rebuilding and repairing damage).
European empires would never seek to conquer territory in Asia, it's too far away. Britain would never seek to conquer India, it's too far away.
China sends its vast fishing fleets to illegally plunder South American fishing waters. It has blanketed much of Africa for resource extraction purposes. It certainly considers Australia as a resource target within its reach. And it's more than that, China had already fallen into the mindset of considering Australia to be increasingly within its sphere of influence and control, which is why the CCP has gotten so angry at Australia in the recent political-economic conflict between the two. They had plans for Australia and assumed they would be dictating terms going forward.
China has literally zero expeditionary abilities. 95% of their military is based on area denial, the remaining 5% on taking Taiwan, which they can barely do as of today.
There is zero evidence that China is developing the capability of invading anyone except Taiwan for the next 25 years, and heaps of evidence to the contrary.
There is stupid and then there is literally physically impossible.
As far as Britain invading India, it's not like if they had just one day woke up and decided to do it. They built up the capability to invade colonies over literally centuries before being able to start the invasion around 1760. Meanwhile China didn't even start building that capability. They don't even plan to deploy stealth carrier craft, up until today their projects are for export only, nor blue water invasion craft, etc...
Anyways, it's almost impossible to invade Australia in 2021. Even the US would seriously struggle.
