The phrase "unprovoked violence" means that an act of aggression or harm is committed without any reason or cause. It implies that there was no action, situation, or disagreement that triggered the violent behavior. Full definition
And all have been guilty of vicious acts of unprovoked violence.» (christianitytoday.com)
As Harris Coulter convincingly demonstrated in his book, «Vaccination, Social Violence and Criminality» the unwanted consequences of human vaccination include sudden unprovoked violence in children. (dogsnaturallymagazine.com)
More often than not, they are depicted by media, specifically in movies, as proponents of unprovoked violence and massive brawls. (bikerkiss.com)