Question is probing an assumption some make that US strikes on Chinese soil would be seen as escalatory (compared to strikes on Chinese forces on or around Taiwan)

Resolves NA if China does not attempt to invade Taiwan OR it does but the US does not attempt to defend Taiwan (before 2040)

Resolves NO if the US DOES attempt to defend Taiwan from a Chinese invasion, and DOES NOT perform military strikes on Chinese soil

Resolves YES if the US DOES attempt to defend Taiwan from a Chinese invasion, and DOES perform military strikes on Chinese soil

Military strikes: anything physical

Chinese soil: PRC 'land' territory including Hong Kong, Macao and offshore islands close to China's coast but excluding any reclaimed land or islands in the South China Sea.

Also excludes land that China claims but does not occupy such as the Senkakus/Diaoyutai and Taiwan itself

(no arguments about legal definitions that I haven't forseen that are not in the spirit of the above definition)

Chinese invasion: I think this is going to be obvious; there should be widespread consensus. An invasion does not need to actually take place*, so long as there is substantial evidence that a credible force to invade Taiwan's main island was being massed on the Chinese coast.

Generally speaking, while you can imagine various scenarios with limited military conflict between Taiwan and China that are not an invasion it's hard to imagine the US being involved in anything short of that. However, I reserve the right to make judgements on whether a scenario constitutes an invasion or not. For this reason I will not bet in this market. If I am no longer active then market participants may appoint a neutral arbitrator if there is disagreement.

*we could imagine that US or Taiwanese actions might prevent it from actually happening