Yeah indeed strategic ambiguity has been the approach they’ve taken so far. If they decided to they could change the approach though. I think it’s unlikely China would carry out the threat if a formal alliance was actually announced since in that case they’d be starting a world war. I think it’s more likely they’d express outrage, protest and perhaps fly some fighter jets over Taiwan, take some steps short of actual war. My worry is that if the situation remains ambiguous China might conclude that the security guarantees are not real and that US would not respond. Having strong credibility there is essential for maintaining peace I think, especially if the intention is to actually respond.