Yes. Certain types of violent responses seem appropriate during, after, and in response to structural threats of force. Very few people (radical or otherwise) argue against theoretical self-defense. I specify "certain types" because for example I do not see sexual assault or torture as compatible with anarchist ends, whereas incapacitating, maiming and killing I can perceive as responses compatible with anarchist goals. I myself would only prefer to engage in defensive violence against sociopaths and supremacists as necessary, preferring other forms of conflict resolution where possible, but I do not exclude the use of force personally or for others. In the dominant culture violence is not only what authorities have done to us, but also what they have deprived us of. I have chosen before to engage in violence rather than summon authorities and for me this path has worked well in multiple instances.