If you don’t have the capacity to win the war, then what good is a defence treaty? There’s no deterrence anyway, and you won’t even honour the treaty. Even if you honour the treaty, you won’t win anyway. That kind of treaty would be useless to Taiwan anyway.
But if you do have the capacity to win the war, that means China is going to loose the war IF you interfere. China looses, US wins. That’s all it matters.
For reference see Harris Formula for deterrence below. The signaling will require US port call and US boots on the ground, because that’s the only signaling that will penetrate the thick blanket of Orwellian Nonsense and reach 1 billion of Chinese. The Chinese people want pictures and videos as proof, otherwise they rather believe in the information provided by party propaganda. The resolve part is easy to verify, because the US Executive Branch has identified that China is an aggressive nation and the threat it poses requires US “whole of nation” approach. The resolve is there.
Capability x Resolve x Signaling = Deterrence.
All three elements, capability, resolve, and signaling, must be present for deterrence to exist. And because we’re doing multiplication, not addition, if any of these elements are missing, you’ve got zero deterrence. Again, if any of these elements are missing, you’ve got zero deterrence.
By capability, I mean all elements of national power - including the military, but not exclusively the military.