Defending networks, information systems, and data within the cyber domain are a necessity for ensuring freedom of maneuver for tactical elements. Defense-in-depth and line defense are forms of defense that the Department of Defense currently uses to conduct defensive cyberspace operations. However, operational and tactical commanders do not have the authorities or means to employ counter effects within cyberspace as they do within the physical domains. Case studies of the Russian attacks on Georgia in 2008 and Ukraine in 2014 demonstrate that passive defensive cyberspace operations are not sufficient to provide protection against a near-peer adversary with sophisticated cyber capabilities during combat operations. By providing an active capability, Defensive Cyberspace Operations-Response Action (DCO-RA) offers a possible solution to the problems of the inadequacy of passive defense at echelons corps and below. The primary obstacles to the implementation of DCO-RA as a viable solution are legal frameworks, capabilities, and the lack of direct precedent from which to learn. However, DCO-RA has analogies in the physical domains of warfare, counterfire and ballistic missile defense, that can provide guidance towards solving the problems of DCO-RA at the operational and tactical level. These analogies serve to demonstrate that the development and employment of DCO-RA is not an entirely new phenomenon of warfare, but rather an instance of a broader pattern. Overcoming an adversary is the art of combining what is possible with what is necessary to achieve defense. At some point the United States must stop being the world's cyber punching bag and counter its adversaries with a few cyber jabs of its own. This research demonstrates that DCO-RA, when fully and properly enabled, is capable of doing just that.

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