> Defending Taiwan (and Japan) is one area where the US would do exceptionally well in any war.

According to a former US State department official (I heard on a recent podcast interview), China never cared to take Taiwan. If they wanted to, all they need to do is cut off access to fresh water from the Chinese mainland.

The US might be able to prevent a ground invasion or counter-attack missile batteries, but the island will fall quickly if China put it's mind to the task.

No, that must be Hong Kong. Taiwan is an island and not connected to the mainland.

Today, probably yes for Taiwan, certainly yes for Japan. But the pace at which the Chinese Air Force is improving you have to wonder if they could eventually develop air superiority over the South China Sea and prevent US surface ships from getting too close. If so, would the Taiwanese fight bitterly, or would they give in? Fifteen years ago a scenario like that seemed like a fantasy. 'And Afghanistan was a mess.

Also, the British didn't have a rival in the North Sea when the Germans conquered Norway.

> They have no rival on the sea

Well other than the 'carrier killer' missiles like the DF-21D.