Is violence justified in pursuit of political aims? if so, when?
Is violence justified in response to violence? Even if it is from organs of the State?
Is violence justified, full stop?
For that matter can violence be waged against property, or is it by definition only against people?

It was a path of folly that led to the outbreak of arson and looting in Bangkok. But imo it was not justified- because the perpetrators did no favours to their cause, a cause which itself is eminently justifiable.