This is circumstance exists all over the world. Would we have fought Argentina for the Falken Islands if Britain had decided not to fight for them?
There are islands off the coast of Japan that Russia claims. If they are "invaded" and Japan does nothing would we intervene?
If Turkey invades Rhodes or the rest of Cypress and the Greeks and Cypriots do nothing do we intervene?
I see more of an advantage to China and the people there if a little of Taiwan's democracy is infused into the Chinese Mainland. Maybe all this rhetoric is test the water of both sides.
If Bush means what he says, you would have to assume that we the USA will help defend those people who are free and now their freedom is taken along with helping those people who wish to be free and democratic and are now taking measures towards that.
Sadly, now they are not.
The only pertinent question to each situation is "is our national security threatened"?
Hubris has, alas, carried us way beyond that simple, old fashioned, pragmatic, conservative, principle.