Would the US go to war to prevent that happening? The short answer is that no one really knows.
Not the military planners in Washington and Beijing, whose job it is to draw up elaborate plans for conflict over Taiwan. Nor, possibly, even America’s commander-in-chief, Joe Biden.
So much would depend on the nature of the attack — and the domestic and international political situation at the time.
As the Cuba missile crisis of 1962 and the 1914 July crisis in Europe both demonstrated, world-shaking decisions about war and peace, are often made in a surprisingly haphazard fashion under the pressure of fast-changing events.
Gideon Rachman FT October 2021
Biden must therefore make it crystal clear to Xi that the US would mobilize its own military resources to defend Taiwan. But will he?