The problem is that if you don't guarantee the freedom of Taiwan and, more importantly, Japan, those countries may decide that the safer thing to do is to switch sides rather than fight alone. Then you are not facing a peer threat, you are facing a coalition that can plausibly threaten to cut off your naval access in the Western Pacific.
Switch to what side? If we're not at war with China, what does it even mean for Taiwan to "switch sides"? More fundamentally, if we don't have declared interests in the South China Sea area, why would we even consider going to war with China. Let them deal with the Norks.
In terms of access to the Western Pacific, all the sorts of threats faced by a US fleet would be faced by a Chinese fleet attempting to operate outside the range of Chinese land-based aircraft. The least useful role for carriers is anti-surface warfare, and if the goal is just to keep the sea lanes open we don't need them. A dozen modern submarines could play hell with any country's ability to maintain trading routes.
That is a bit naive. You may think countries don't "switch sides" but take a look at Europe after 1989. East Germany joined West Germany and look what happened to Russian influence over Poland and the Baltic States.
If Japan and Taiwan allowed China to base its navy or air force on their territory, the US navy would effectively be pushed back to Hawaii. If China chose to threaten Vietnam, South Korea, Australia.. there would not be much we could do about it.
>If Japan and Taiwan allowed China to base its navy or air force on their territory, the US navy would effectively be pushed back to Hawaii.
Yes, and...? If they're happy with China guaranteeing their security, then I don't see the big problem. As to the other countries... how is this my problem? Did we help Vietnam the last time China invaded in 1979? Is first-world island nation Australia incapable of defending itself?
> If they're happy with China guaranteeing their security, then I don't see the big problem
China does not guarantee their security or offer to, and they wouldn't be happy with it. In contrast, the U.S. has treaties to defend them, on which they heavily rely and which have maintained peace in the region for over 50 years.
