Defining the “Domain” in Multi-Domain

By: Jared Donnelly and Jon Farley


Estimated Reading Time: 7 Mins 

“First, if the concept [Multi Domain] is to be truly joint and multi-service, we need clarity and alignment in how we talk.” General Stephen Townsend, US Army TRADOC Commander

“Multi Domain” is the word du jour of the defense enterprise. While there are plenty of philosophical discussions on the future of warfare, the important dialogue regarding the definition of domains have been largely untouched. There are a lot of smart people trying to wrap their heads around what this means for the employment of forces, but much of this churn is currently wasted, as the defense community does not have a basic definition for the word “domain.” Until we understand what constitutes a domain, and just as importantly what does NOT, we cannot move forward with the paradigm shift that is multi domain.

Doctrine does not help us with the definition of a domain. Joint Publication 3-0 does not define the term, though it uses the word from time to time. The closest it gets is in describing the Operating Environment (OE). Conceptually this is similar, but the notion of an operating environment is not the same as a domain. By the JP 3-0 definition, an OE can encompass some or all domains depending on where the commander needs to operate. This is much closer to the multi domain concept as a whole where the commander will utilize a variety of domains to achieve their operational and strategic goals.

Where joint doctrine does discuss domains it often uses the term in ways that provide little clarity as to what resides in the domain or where the boundaries lie between domains. For example, in JP 3-0 cyberspace is defined as a “…global domain within the information environment” (JP 3-0, IV-2) while the information environment is described as “…the aggregate of individuals, organizations, and systems that collect, process, disseminate, or act on information” (JP 3-0, IV-1). To further complicate things, JP 6-0 states that the Electromagnetic spectrum (EMS) “…transcends all physical domains and the information environment and extends beyond defined borders and boundaries” (JP 6-0, I-6). This leaves warfighters with a domain (cyberspace) that exists within a milieu of individuals, organizations, and systems (information environment) that is transcended by the electromagnetic spectrum. Finally the warfighter is asked to fight and win in an Operating Environment (OE) that “…encompasses physical areas of the air, land, maritime, and space domains: the information environment (which includes cyberspace); the electromagnetic spectrum; and other factors” (JP 3-0, XIV).

OTH, multi-domain operations, emerging security environment

JP 5-0 offers the diagram above as example of the OE, comprised of the stated domains: Land, Air, Maritime, Space, and Cyberspace. This graphic is an attempt to visually depict the interrelationships of domains, however it still does not inform the actual definition of the term.

The US Army’s Training and Doctrine Center (TRADOC) also dances around the term with respect to Multi Domain battle by stating: “all domains are contested – land, air, maritime, space and cyberspace, and across the electromagnetic spectrum.”

The physical domains of land, air, maritime, and space are generally well understood conceptually – to the extent that joint doctrine does not feel the need to define them, but the non-physical areas of cyberspace, information environment, and the electromagnetic spectrum are much more difficult to conceptualize and bound within a constructive definition. That often leads us to situations where operations in these non-physical domains are ill-defined, ineffectual, or non-existent, opening critical vulnerabilities to adversaries. As an example, electromagnetic interference (EMI) is rapidly becoming the Achilles heel of military operations. Maneuver within the electromagnetic spectrum is required by most warfighters, from basic radio operators to electronic warfare assets to satellite sensors. The sheer number of electronic devices on the battlefield, which travel through an ill-defined and coordinated EMS, are leading to routine blue-on-blue EMI fratricide. This could only be compounded if our opponents actively attempt to deny access.

This discussion is even more challenging when working with the North Atlantic Treaty Organization (NATO) partners because NATO doctrine uses the term domain to mean something else entirely. The NATO Combined Operations Planning Directive (COPD) uses the term domain in reference to the Political, Military, Economic, Social, Infrastructure, and Information Systems (PMESII), which the JP 5-0 refers to as systems. NATO doctrine looks at the concept of domains as dimensions of an operation environment “…including its land, air/space, maritime dimensions, as well as the PMESII systems of main adversaries…” (COPD 4-7). Therefore, with no doctrinal definition of a domain, we are forced to look to other thinkers for insight.

William Dries in a War on the Rocks commentary used the Miriam Webster definition for domain: “a region distinctively marked by some physical or virtual feature(s).” This is a good foundation for the term, but is more refined by Peter Garretson: “A domain is a space in which forces can maneuver to create effects.” This definition is closer, but we would argue that it still misses some salient points.

Other researchers working in the field of information operations, Patrick D. Allen and Dennis P. Gilbert, have suggested a definition for domain as “The sphere of influence in which activities, functions, and operations are undertaken to accomplish missions and exercise control over an opponent in order to achieve desired effects” (Allen and Gilbert, 133). The latter part of this definition addresses the relation of the domain to the operational requirements. This is an important distinction to make because the purpose for the existence of the domain concept is to provide a framework for focusing action in pursuit of strategic aims, however this definition does not fully encapsulate what we believe to be the full scope of a domain.

We offer the following definition of a domain, first proposed by Jeffrey Reilly, as a “Critical macro maneuver space whose access or control is vital to the freedom of action and superiority required by the mission.”

The first segment of this definition is a critical macro maneuver space.” This phrase begins by implying that a domain starts with maneuver. As one of the Joint Functions, movement and maneuver is…disposition of joint forces to conduct operations by securing positional advantages before or during execution. This function includes moving or deploying forces into an operational area and maneuvering them within the timeline and to the operational depth necessary to achieve objectives. JP 1-0, I-19

The maneuver in a domain is often a unique, defining feature that separates domains from one another. But maneuver alone is not sufficient for a domain. The term macro helps simplify the definition by imposing some level of constraint. Without macro, one could argue that any distinctive feature would constitute a new domain, such as the difference in maneuver at 1k feet versus 50k feet, or the difference in maneuver in the infrared (IR) spectrum versus the radio frequency (RF) spectrum. This is the most difficult part of the definition, but one which must be clearly understood in order to be effective. The tension is simplicity versus specificity, and there are compromises with each.

The next segment is “whose access or control is vital.” This segment implies that we need access or control of a medium in order for it to be a domain. For example, prior to the launch of Sputnik in 1957, the space domain physically existed, but was not operationally accessible. If the ability to maneuver through, access, or control, a medium is vital to the mission, then it meets the definition of a domain.

The final segment of the definition is “freedom of action and superiority required by the mission.” This segment refers to the mission, and the ability to freely act and gain superiority in a domain. This closely ties to the definition of a center of gravity in JP 5-0: “The source of power that provides moral or physical strength, freedom of action, or will to act.” Superiority may come in the form of dominance, such as air superiority, or denial, such as in the electromagnetic spectrum. Ultimately, this ties the definition back to the mission, providing an anchor to the true purpose of maneuver through domains.

In the end, terms matter. The military is actively pursuing a multi domain concept, with no understanding of the term domain. This attempt to provide a foundational definition is the beginning of that conversation. Until we understand the building blocks on which we are depending, the multi domain concept cannot be explored to the level it deserves.

*Featured Image courtesy of Lockheed Martin*

LCDR Jon “Tike” Farley is an instructor at the Air Command and Staff College who teaches in the Multi-Domain Operational Strategist program. He is an F-18 Pilot with multiple deployments to the 5th Fleet AOR, supporting operations in Iraq and Afghanistan. Email: 

Dr. Jared Donnelly is an Assistant Professor at the Air Command and Staff College. He teaches in the Multi Domain Operations Strategists program for the Department of Future Security Studies. Email: 

The views expressed are those of the author and do not necessarily reflect the official policy or position of the Department of the Air Force or the U.S. Government.

OTH, multi-domain operations, emerging security environment

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13 thoughts on “Defining the “Domain” in Multi-Domain

  • September 17, 2018 at 1:17 pm

    The authors are correct in their conclusion that terms matter and that a clearer understanding of the term “domain” across the joint and combined planning community would facilitate growth, integration and application of the multi-domain concept. Their suggested definition is easily applied to the physical domains (air, sea, land, space) wherein the military mission requires that we maintain freedom of action while limiting the actions of those who would deny us mission accomplishment. But what about the actors? Shouldn’t we pay as much attention to the actors as we do to the potential actions they might undertake? Does the human domain fit within the proposed definition?

    Assuming that mission analysis supports the conclusion that a desired end state can only be achieved, in whole or in part, through the actions or restraint of individuals, groups or segments within an opposing population, it is therefor critical to our success. The human domain is certainly “macro” in the sense that it encompasses all human decision makers, only being scaled down as mission requirements dictate. Maneuver in this domain is represented by various forms of influence that can result in shifts of attitude and behavior needed for mission success. And, while we may never be able to fully control the actors in the human domain as effectively as we can control their actions in the other domains, we need access to the decision-making battle space to provide alternatives to hostility. It does seem to fit.

    Unlike the physical domains, our understanding of the human domain as a planning consideration is minimal. And yet, without people and their actions, what threats would we face from the other domains?

    • September 17, 2018 at 2:21 pm


      We would completely agree with your analysis. Personally, I believe that all of the actions in the other domains are focused on creating an end result, which is a change in behavior in the human domain. As a military, the US tends to focus on targets instead of the more nuanced human impact. Codifying the human domain would allow a discussion on desired impact of an operation, instead of simply how to hit those targets more efficiently.

      Thanks for your input, we hope to keep this conversation going and establish a baseline for collective growth and understanding.

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  • July 14, 2020 at 7:42 am

    “The United States greatly decreases its ability to prevail in a multi-domain fight so long as we continue to cede the Human Domain to our adversaries.” Colonel (Ret) Robert C. Jones

    War is fundamentally a human endeavor. As such, strategic concepts are grounded in the durability of human nature. The empowering character of the post-Cold War explosion in information technology has shifted the relative balance of power from governments to populations in unprecedented ways, making population-based activities the most dynamic arena of competition, both within and between states.

    And yet nothing strikes greater fear in the hearts of the services than the mere mention of adding a “human domain.”

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