Marcus Aurelius says, “the best revenge is to be unlike him who performed the injury.” Does that mean we can’t act in retaliation if someone uses violence against us? No. Does that mean we can’t perform a similar act towards someone who just performed an aggressive act towards us? No.
Marcus Aurelius was meaning that we shouldn’t have the same intention and negative passions that led someone to injure us. It doesn’t mean that if a nation attacks another nation, the nation attacked shouldn’t respond in force. If it meant that, then Marcus Aurelius would be a hypocrite responding in force against the barbarian threat against the Empire.
Stoicism is a virtue ethics, so it cares about the character and intent of the agent. If someone attacks you violently, you might have to attack back but with a whole different intention than the one that the other person had. Your intention is to neutralize the threat. The intention of the person who caused the injury is to cause injury because they’re mad at you. Very different from a virtue ethics stance.