As warfare evolves, new technology pushes the limits of acceptability and operations in cyberspace are no different. If attacks in cyberspace are assaults of one state against another, then the framework of Just War theory should still apply and Michael Walzer’s Legalist Paradigm provides a clearer lens on when an armed response to a cyber attack is morally permissible. While some parts of Just War theory directly apply to responses to Cyber Attacks, the others do not, beginning with Just Cause. Walzer describes Just Cause in terms of the natural rights of the citizens of a state, and when a cyber attack interrupts the ability of those citizens to make a life together or the “safe space” they create, then a physical response to a cyber attack could be justified. This paper outlines the relationship between Walzer’s Legalist Paradigm and justification for physical responses to cyber attacks, with the intent of providing senior leaders with a framework for those responses.