China for the last 60 years or so has been threatening to use it's military force on Taiwan if it formally declare its independence. Although the recent warming in trade, business and maintaining of the Status Quo under one China policy has ease some of the tension. Any radical political move such as the declaration of independence would immediately reignite any mentality of PRC military invasion (recovering) of Taiwan. I believe the last time China threaten/display with military force was in 1995-96 with third Taiwan strait crisis.
Mainland China claims that Taiwan is a self governing province. Any further attempts at full independence will likely be met with a military response. China has been developing further military technology for decades for the specific purpose of formally reclaiming the island as a part of the Beijing controlled China.
Taiwan has finally gained independence and is recognized as a separate from China. There is no reason for China to respond militarily against Taiwan Independence. Taiwan won its independence with war efforts that earned the independence from China. China should recognize Taiwan as an independent nation with its own laws.