In Defense of the Theater Army

Lt. Col. Nicholas R. Simontis, U.S. Army

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The Army’s ability to set the theater is essential to preventing conflict and, if deterrence fails, allowing the Joint Force to seize the initiative while protecting the force and restricting the enemy’s options.

—The U.S. Army Operating Concept

The theater army and its theater-assigned Army forces set the theater and the joint operations area for the employment of landpower in contingencies and campaigns.

—Theater Army, Corps, and Division Operations

Theater armies have a rich and storied history, conjuring images of Courtney Hodges commanding First Army, George Patton commanding Third Army, and Alexander “Sandy” Patch commanding Seventh Army, along with Eighth Army commanded by Robert Eichelberger in the Philippines during World War II, and later by Matthew Ridgeway in Korea.1Following combat operations, the roles of theater armies evolved to suit operational and strategic requirements, executing missions ranging from occupation duties to training Army Reserve and National Guard units. In a more recent example, Third Army served as combined forces land component command (CFLCC) during Operations Enduring Freedom and Iraqi Freedom, and later as combined joint forces land component command (CJFLCC) and then combined joint task force (CJTF) for Operation Inherent Resolve (OIR). Despite this history and the unique role theater armies fill, these headquarters are a recurring target for reduction and possible elimination in the ongoing efforts to reduce force structure.

According to doctrine, theater army responsibilities are straightforward. However, possibly due to the fact that most officers have little experience with theater armies, there is a great deal of misunderstanding regarding their roles.2 Because of this, theater armies are a target of convenience in the quest for force reduction, but recent recommendations go too far, eliminating vital theater army roles and functions. In reality, the responsibilities of theater armies are far more expansive, requiring specialized sets of capabilities.

Contrary to misunderstandings regarding their doctrinal role in today’s environment, theater armies are becoming more strategically necessary than ever. Owing to their unique capabilities, theater armies can form the backbone of joint or multinational forces, serving as a joint or multinational force integrator and providing a platform that facilitates joint force interdependence.

This article proposes that theater armies should be retained. They have provided and can continue to provide viable options for conducting significant operations using the principles of mission command. These include maintaining a vital, persistent forward presence; conducting shaping through theater security cooperation and military engagement; providing regional expertise; and laying the foundation for, and forming the gateway through which follow-on ground and joint forces can deploy and fight as necessary.

From Reduction to Elimination

Recommendations to modify the organizational structure of theater armies/Army service component commands (ASCCs) have been ongoing for some time. Early efforts at reduction originally sought to scale down only the mission command responsibilities of theater armies, calling into question their ability to command operational forces, particularly for extended periods. In 2011, Field Manual (FM) 3-93, Theater Army Operations, signaled this intent. It recommended the elimination of the operational command posts (OCPs) originally intended to form the foundational structure for joint task forces (JTFs) or joint force land component commands (JFLCCs) designated to run major operations.3 In 2014, FM 3-94, Theater Army, Corps, and Division Operations, which replaced FM 3-93, echoed this same sentiment, stating, “theater armies have limited capabilities to serve as a JTF or JFLCC, and then for only a short duration or limited contingency operation.”4 However, FM 3-94 omitted a key piece of contextual information found in FM 3-93: the proposed addition of a fourth corps headquarters to allow the theater army “to be relieved of its previous responsibility to transition to a JTF, JFLCC, or ARFOR [Army forces] headquarters.”5 This fourth corps headquarters would permit a rotational mission command structure, while maintaining a corps headquarters for contingency needs. Clearly, the intent of FM 3-93 and FM 3-94 was to leave theater armies/ASCCs in place, merely removing direct mission command responsibilities and relying instead on corps headquarters to execute those responsibilities when necessary. The Department of the Army (DA) did, in fact, eliminate OCPs in later years, but without establishing a fourth corps headquarters as originally called for. Now, some observers recommend the elimination of ASCCs altogether.

The Elihu Root Study: The Total Army proposed eliminating theater armies and replacing them with corps headquarters.6 Several months later, David Barno and Nora Bensahel made the same recommendation, proposing the replacement of theater armies with “dual-hatted operational headquarters that also have warfighting capabilities,” which can be translated as corps headquarters.7 In reality, however, replacing theater armies with augmented corps headquarters merely shuffles the deck while actually reducing overall Army expeditionary capability unless additional corps headquarters are added, a requirement that runs counter to the current goal of reducing structure. All of these proposals are shortsighted and fail to appreciate the current and potential roles of theater armies.


Understanding Theater Army Roles and Responsibilities

The requirements for theater armies and their several command relationships are delineated in Army Regulation 10-87, Army Commands, Army Service Component Commands, and Direct Reporting Units, and laid out doctrinally in FM 3-94. These requirements center on providing administrative control over Army forces in theater, assuming extensive theater sustainment responsibilities, providing operational control of designated Army forces in theater, supporting theater security cooperation and theater engagement plans, and setting the theater—establishing and maintaining conditions for the employment of land forces and support to joint forces in the theater.8 Yet, merely reviewing a list of these extensive and wide-ranging requirements does not lend a holistic appreciation of the unique roles fulfilled by theater armies. An alternate way to understand theater army roles is in terms of a conduit and four infrastructures, as the following paragraphs describe.

A theater army/ASCC serves two masters—the Department of the Army (DA) and the geographic combatant commander (GCC), acting as a conduit between the two headquarters. In this conduit role, the theater army strives to balance GCC theater requirements with Army capabilities, while advising the Army on theater-specific requirements that help shape the force, informing structural, manning, and equipping decisions. This input, shaped by the current and projected operational environment in theater, can then inform the development of the Army’s input to the Planning, Programming, Budgeting, and Execution process. This role as a conduit between DA and the GCC is thus critical to helping the Army tailor its structure in order to execute its mission of “providing prompt, sustained land dominance across the full range of military operations and spectrum of conflict in support of combatant commanders.”9

In addition to acting as a conduit, a more practical way of understanding the roles of theater armies is in terms of their responsibility for establishing and maintaining four overarching infrastructures to support the theater; the theater army, through supporting commands, maintains the theater-wide sustainment, medical care and support, communications, and intelligence infrastructures necessary to support land forces.10 These infrastructures together support the GCC’s theater campaign plan and form the foundation necessary to execute the full scope of military operations, from combined exercises by rotational forces to contingency operations in response to crises or military conflicts.

In essence, these infrastructures together comprise the theater architecture that enables a wide range of options for land forces as well as supporting the joint force through Army support-to-other-service functions. Moreover, particularly in the U.S. Central Command and U.S. Pacific Command areas of responsibility, the theater-setting functions and forward platforms provide the groundwork for strategic force projection ranging from special operations teams to conventional combat divisions that assure access in the face of ongoing area denial efforts to limit access to contested regions.

Attendant Functions

Broadly speaking, the theater Army provides the four infrastructures discussed in addition to handling statutory Title 10 responsibilities and serves as a DA-GCC conduit. These activities encompass the overall theater army functions. However, there are several other more narrowly scoped specific functions wrapped into these broad functions that merit particular attention.11

Mission command. First and foremost among these functions is mission command. Previous and current doctrine describe theater armies as having only limited-duration mission command capability, yet U.S. Army Central (USARCENT) has executed this responsibility repeatedly, controlling ground operations in Afghanistan from 2001 to 2002 as the CFLCC, then becoming the CFLCC for operations in Iraq in 2002.12 More recently, U.S. Central Command designated USARCENT as the CJFLCC for operations in Iraq and Syria in September 2014, and then as the CJTF-OIR in October 2014.13 While the headquarters did require joint augmentation, the speed with which USARCENT established the CJTF was only possible due to the forward presence of the OCP in Kuwait, along with the enabling commands providing the necessary support infrastructure for the rapid reception and integration of joint and coalition partners. Contradicting doctrine, USARCENT served dual roles as the theater army and the CJTF for fifteen months until relieved by III Corps.14 This suggests that a better way to think of mission command by theater armies is as a viable option for establishing a CJFLCC or a CJTF quickly, thereby providing rapid response and setting conditions for a corps or other headquarters to deploy and assume responsibility when appropriate.

Joint security coordinator. A second important capability of theater armies lies in their potential role as joint security coordinator (JSC) for the GCC, if so designated. The protection cell within the theater army generally has staff responsibility for this function unless a joint security coordination center is established. The protection cell assesses risks, develops plans, and integrates and synchronizes actions and activities with a goal of protecting the force. The theater army often resources many of the necessary capabilities to meet JSC requirements, and the JSC role often includes responsibility for joint and multinational forces. The necessity and importance of the JSC role will likely increase as the trend toward hybrid or gray zone conflict continues and expands.15

Fires. A third important and often-overlooked capability of a theater army concerns fires, specifically, integrated air defense (IAD) and cross-domain joint fires. The theater army’s IAD cell facilitates planning from a ground perspective in close coordination with the area air defense coordinator, supporting the joint force commander’s air defense priorities. Elements of the IAD cell, along with subordinate air defense artillery brigades, often work with regional partners (within the limits of disclosure) to ensure overall synchronization and integration of IAD capabilities, as well as to build partner capacity. This is an area of increasing concern in the face of anti-access/area denial threats and the growth in adversary missile and rocket capabilities. The fires cell and its joint fires section perform a similar role, integrating Army and joint fires capabilities focused on regional planning, supporting GCC theater and contingency planning, and availing themselves of opportunities to conduct combined and cross-domain training and build partner capacity.

The integration of Army AH-64 Apaches operating from naval surface platforms that frequently occurs in the U.S. Central Command area of responsibility provides an apt example of cross-domain capability routinely practiced by USARCENT and U.S. Navy Central. This is an area ripe for further development.


Planning. A final important capability of theater armies concerns theater-focused planning from a land force perspective. The theater army commander and staff immerse themselves in theater events on a daily basis, interacting frequently with their counterparts from other components, GCC planners, and counterparts with regional partners, and often with division and corps planners for input to contingency plans. A theater army, by its very nature, is a planning headquarters, constantly looking at the environment and into the future, asking “what if?” This planning role is particularly important given the theater army’s conduit role described above. The interactions between the theater army, the GCC, and DA should enhance the effectiveness of planning by all three headquarters.

Additional Thoughts

Theater army structure and organization can and should be improved, but that does not imply slashing structure across the board, as occurred with the elimination of OCPs, or scrapping the formations altogether and replacing them with augmented corps headquarters, as some recommend. In the case of USARCENT, the headquarters mitigated the elimination of the OCP through the assignment of a rotating National Guard division headquarters.16 While this is a viable interim fix, there is no net savings in personnel; there is merely a change in their origin and the funding process, shifting the burden from the active Army to the National Guard. Furthermore, there is a longer-term cost to the quality of regional relationships and military engagements due to the more frequent turnover of OCP personnel. Similarly, replacing theater armies with augmented corps headquarters merely swaps headquarters and shuffles personnel with a net effect of reducing Army expeditionary capability unless additional corps headquarters are added, which is at best an unlikely prospect. Replacing theater armies with some other headquarters is needlessly disruptive and provides no evidence of demonstrable structural improvement, efficiency, or improved effectiveness.

The alternative is to take advantage of one of the unique qualities of theater armies—the ability to tailor them appropriately to the theater in which they serve by adjusting their organization to reflect theater and GCC requirements efficiently. This already occurs, but opportunities for improvement remain. An example is to align and synchronize the various sustainment functions between G4, Theater Sustainment Command, Expeditionary Support Command, and the sustainment brigades to eliminate duplication of functions. Along the same line, sustainment functions should be integrated with other services to improve interoperability and sustainment efficiency while eliminating duplication of services across the joint force. Significant opportunities for developing such “joint force interdependence” exist and should be pursued.17

A final thought on theater armies is that they provide a unique platform for developing strategic leaders as well as for increasing the strategic and joint competence of the theater army staff. Due to the wide-ranging roles of a theater army, the commander and staff interact regularly with DA and the GCC, along with functional component commands, the other components, Army direct reporting units such as Medical Command, Network Enterprise Technology Command, and U.S. Army Intelligence and Security Command, as well as regional counterparts in theater. Thus, senior leaders through junior majors and captains enjoy opportunities to regularly interact with other services and headquarters that are not available elsewhere in the Army.

The broad focus required to establish and maintain the four infrastructures obliges the commander and staff to take a more wide-ranging view of these functions than is possible in most other Army assignments. The theater army’s unique role, the many niche capabilities it fills for the GCC, and the directed responsibilities and functions under Title 10 that comprise Army support to other services require staff officers in a theater army to interact regularly with higher and adjacent Army and joint headquarters. The theater army serves as a bridge from the strategic to the tactical, serving GCCs and the joint force, and providing its leaders and staff with an operational viewpoint that is unique in the Army.


Recognizing the need to project forces around the world, the Army Operating Concept describes how the Army intends to prevent conflict, shape security environments, and win wars, all while operating as part of the joint force and working with multiple partners.18 Accordingly, the Army Operating Concept describes twenty required capabilities including functions such as developing a high degree of situational understanding; conducting security force assistance; integrating joint, interorganizational, and multinational partner capabilities; and setting the theater to provide strategic agility.19 Theater armies execute eleven of the twenty capabilities listed, and they contribute in some fashion to most of the remainder, demonstrating they are key to maintaining strategic credibility.20

Theater armies are the face of the land component to our regional partners, demonstrating U.S. commitment, assuring access through forward presence, and maintaining the ability to project land forces wherever and whenever needed. Clearly, the singular role and capabilities of theater armies will only become more important in the current and anticipated environment; they cannot be replaced, nor should they be.

The author is indebted to Lt. Gen. James L. Terry, U.S. Army, retired; Dr. John A. Bonin, professor, U.S. Army War College; and Col. Jin H. Pak, U.S. Army, for their valuable insights and comments for this article.


Epigraph. U.S. Army Training and Doctrine Command (TRADOC) Pamphlet (TP) 525-3-1, The U.S. Army Operating Concept: Win In A Complex World (Fort Eustis, VA: TRADOC, 31 October 2014), 23.


Epigraph. Field Manual (FM) 3-94, Theater Army, Corps, and Division Operations (Washington, DC: U.S. Government Publishing Office [GPO], 2014), para. 2-10.


  1. Regarding terminology, while many of the force structure recommendations pertain to Army service component commands (ASCCs) generally, this paper focuses more specifically on ASCCs provided by the Department of the Army to geographic combatant commands, which serve dual roles as theater armies and ASCCs. This paper uses the term “theater army” in reference to these particular headquarters.
  2. Nelson L. Emmons, Transforming the Army Service Component Command to a Theater Army (Carlisle Barracks, PA: U.S. Army War College, March 2013), 1.
  3. FM 3-93, Theater Army Operations (Washington, DC: U.S. GPO, 2011 [now obsolete]), x.
  4. FM 3-94, Theater Army, Corps, and Division Operations, para. 2-1.
  5. FM 3-93, Theater Army Operations, x.
  6. Syed Najeeb Ahmed et al.,Elihu Root Study: The Total Army"> (Carlisle Barracks, PA: U.S. Army War College, 2016).
  7. David Barno and Nora Bensahel, The Future of the Army: Today, Tomorrow, and the Day After Tomorrow (Washington, DC: The Atlantic Council, 2016), 18.
  8. Army Regulation 10-87, Army Commands, Army Service Component Commands, and Direct Reporting Units (Washington, DC: U.S. GPO, 2007), 1-2, 4-13; FM 3-94, Theater Army, Corps, and Division Operations, paras. 2-1 to 2-12.
  9. “Mission,” website, accessed 24 May 2017,
  10. James L. Terry, U.S. Army, retired, used this example on numerous occasions during his tenure as commander, U.S. Army Central/Third Army, 2013–2015. Used with permission.
  11. Working-Capital Funds, 10 U.S.C. § 2208 (2015).
  12. “USARCENT [U.S. Army Central] Historical Summary (1918–Present),” USARCENT website, accessed 24 May 2017,
  13. James L. Terry, “Curtain’s Always Rising For Theater Army,” Army Magazine 66, no. 2 (February 2016): 49, accessed 11 July 2017,
  14. Ibid.
  15. For additional information on joint security coordinator duties and responsibilities, see Joint Publication 3-10,Joint Security Operations in Theater (Washington, DC: U.S. GPO, 13 November 2014).
  16. Dr. John Bonin (professor, U.S. Army War College), e-mail to author, 7 December 2016. Used with permission.
  17. Adm. Jonathan Greenert, “Navy Perspective on Joint Force Interdependence,” Joint Force Quarterly 76 (1st Quarter, January 2015): 11, accessed 11 July 2017,
  18. TP 525-3-1, The U.S. Army Operating Concept, i.
  19. Ibid., 31–33.
  20. Ibid. The eleven capabilities are [in abbreviated form]: (1) develop and sustain a high degree of situational understanding; (2) shape and influence security environments; (3) provide security force assistance; (4) prevent, reduce, eliminate, and mitigate the use and effects of weapons of mass destruction and chemical, biological, radiological, nuclear, and explosive devices; (5) assure uninterrupted access to critical communications and information links; (6) develop agile, adaptive, and innovative leaders; (7) project forces; (8) establish and maintain security across wide areas; (9) integrate joint, interorganizational and multinational partner capabilities; (10) set the theater; and (11) coordinate and integrate Army and joint, interorganizational, and multinational fires.


Lt. Col. Nicholas R. Simontis, a U.S. Army strategist, is the chief of strategy at Third Army/U.S. Army Central. He holds a BS in engineering from the University of South Carolina, an MA in security studies from Kansas State University, and an MMAS in theater operations from the School for Advanced Military Studies, Fort Leavenworth, Kansas. Prior to his current assignment, he was a lead planner with Combined Forces Command/U.S. Forces Korea, and he served previously at Third Army/U.S. Army Central and Combined Joint Task Force– Operation Inherent Resolve.

Sept-Oct 2017