I mean, if you assume that you've already won, then yeah, you've already won. Rather tautological.
It's not tautological. It's logic.
As I point out, if there are American airbases still operating in Japan in the 1IC, these are more of a threat to mainland China than any base in the 2IC.
So there's no point developing (more expensive) long-range systems for the 2IC and beyond, unless you assume that Japan can be neutralised.
Remember that this logic is driving China's very expensive weapons development programmes.
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It also means that even if Japan is additionally fortified, China has the capacity to redirect resources from systems designed for the 2IC to the 1IC, and ensure that Japan is neutralised
By the time Japan is neutralized, I expect Guam to be little more than empty hangars. Because that means they've already commited and lost all of their assets defending Japan.
If there is a war, I expect the Chinese military to aim for air superiority over both the 1IC and 2IC - right from the beginning of such a hypothetical conflict. So there will be assets located in both the 1IC and 2IC. Guam represents a "safer" base in that it is further away, and is not subject to Japanese political control.
Remember the background.
1. Biden and the previous Japanese Prime Minister both publicly stated that they had the option of going to war with China.
2. Ray Dalio and the late Henry Kissinger also publicly stated that the rest of the world sees the USA as being "overly aggressive" towards China. And in recent months, China has been on the receiving end of an even more aggressive America. (Caveat here, in that the rest of the world has been subject to American bullying)
What is the logical Chinese response?
If you ignore the undervalued exchange rate, the Chinese economy is approaching twice the size of the US, in terms of real output of goods and services. So China should be able to build a larger military and still bankrupt the US in an arms race. Today, if you look at procurement of equivalent naval and air platforms, China is buying ~2x more stuff every year.
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So tell me what the military balance looks like in 2035 with respect to China-Japan-US.
I've already outlined what I think are the core power projection elements that China would use against Japan.
And I'll add that the USAF presentation states that China has a 4x speed advantage in weapons development and a 20x cost advantage in equivalent hypersonic missiles. Granted, these are the more extreme examples, but you get the idea.
Also, Russia currently produces about 5000 Shaheed Type cruise missiles per month, and these are relatively simple to produce.
Then remember that China's overall manufacturing sector is ~90x larger than Russias. (NB Not that I expect China to actually produce or need anywhere near 450K shaheeds per month)