Taiwan since 1949 has lived in a perpetual state of strategic ambiguity. Lin's book "Accidental State" show how this came about historically in the early 1950s. The US remains at all times ambiguous in its commitment, it seems to me, and I wonder whether anything has really changed with the Biden administration. And much as the PRC sabre rattling is unsettling, the political risk to Xi of launching an all out attack that might fail are huge (not to mention the logistics, which I don't think the PLA has the capacity in the context of the Strait and the Taiwan coast).