One aspect of this very serious problem, that parents and educators may neglect, is that preventing a child from becoming aggressive, violent, or hurtful can be as important as stopping bullying in its tracks. The harsh reality, at any age, is that hurting individuals in one way or another can hurt others. Chalk it up to projection or transference or whatever paradigm you like but the consequential inevitability remains the same.
Recognizing that a child is hurting should remain the universal focus and early interventions must become standard. Emotional regulation training, anger management skills, and support unconditional is what should be in place for all children.
It may at times seem that society tends to focus on disarming and de-escalation rather than prevention. Heal the hurt, focus on early detection of troubled youths, and prevent the potential for a cycle of harm.