A Chinese attempt to take back Taiwan would be like a replay of Okinawa. They will try to starve out Taiwan by attacking its merchant shipping with long-ranged anti-ship cruse missiles launched from land or aircraft. When the US goes to convoy the shipping into Taiwan they will switch to attacking our warships, knowing that the US cannot tolerate any sort of casualties. They will also bombard Taiwans ports and airfields with SRBMs in order to totally disrupt the islands supply and communications with the outside world.
The beauty of this is that if it doesnt work they can still say that they repulsed a attempt by the US and their anti-revolutionary lackys in the rebellous province from spreading the counterrevolution to the mainland. They can still clame victory and save face.
Bush is right to challenge them now, because they need at the very minimum another decade to revitalize the fossillized PLA. And in particular they need to rebuild their nuclear deterant force. Right now it isnt much of a obstical to us at all. They have far fewer ICBM's than we have B2's and ALCMs, their missiles are old liquid fueled types that require at least a half hour from the GO command to launch and cannot be left fueled and ready for very long before the launch command, nor can they quickly or easily be turned around again to be ready to launch. And we think we know where they all are, where they are built, and the C3 nodes that can control them. Their silos and bunkers are vulnerable to the new penetrating weapons that we built to defeat Iraq's bunker systems. We could wipe out their nuclear force in one afternoon, well before they could launch, without using nuclear weapons ourselves- and they know it. Which is why they are getting so irate with us at the moment- they are scared. They know that they are in a period of relative weakness.
Right now is the perfect moment for Taiwan to declare independance from China. The Chinese cannot [i]at this moment[/i] respond effectively militarily. They are however working very hard to change this, each year that goes by it will be more difficult for Taiwan to do this without risking a very violent response from the mainland.