As Shilao like to use as an example: is it outside of ROC's ability to fire several Hsiung Feng IIE missiles loaded with VX at major PRC cities? If it is within their capability, can PLAAF guarantee to intercept all of them? Can we assume ROC government won't resort to it in times of war?
You can argue that such an attack would draw nuclear retaliation from PRC, but that won't bring back the dead would it?
Therefore ROC is very much a threat and why peaceful reunification is still preferred. Don't say it won't happen, the chances of peaceful reunification has in fact increased in recent month due to events like 馆长's visit and the failed Recall.
