It's called stochastic terrorism or stochastic violence. Essentially people are made increasingly angry and violence prone. Either the object of their anger is inaccessible or too diffuse to actually target.
As a result, random acts of semi-targetted violence become increasingly common. If your objective is to create an atmosphere where people have a higher baseline level of fear, which can drive irrational reactionary behavior, it does wonders. It's also great at increasing violent acts against people you dislike without explicitly calling for it.