China already declared that it will use force in Taiwan if "possibilities for a peaceful reunification should be completely exhausted". From Chinese Anti-Secession Law: Article 8: In the event that the "Taiwan independence" secessionist forces should act under any name or by any means to cause the fact of Taiwan's secession from China, or that major incidents entailing Taiwan's secession from China should occur, or t…
With that being said, it's not that simple. Bluster isn't just a political tactic -- it also enables the military to slowly chip away at norms and edge closer towards a strategic advantage (e.g.: progressively violating more and more of Taiwan's sovereign airspace). If the party could have things their way, the military would merely continue pushing the envelope until one day a D-Day assault force seemingly randomly washes up on Taiwan's doorstep.