As a key organizational and operational construct within the highest levels of the United States’ military, combatant commands – along with their commanders – play significant roles in U.S. defense policy. These commands, organized either on a geographical or functional basis, provide effective command and control of military forces, regardless of branch of service, in peace and war. By their nature, they offer U.S. defense policy and application of military force several benefits, but likewise face several challenges.

The combatant command structure emerged out of an evolution, prompted by historical circumstances, in the military’s approach to force unity and command and control. Prior to the Second World War, the services operated independently. Coordination between branches of the armed forces was frequently marred by bureaucratic distrust and service rivalry. The experience of the Second World War, particularly in the Pacific theater, demonstrated the operational pitfalls of this arrangement; differences between the Army and Navy precluded any sort of consistent unified command. While commanders were able to work together to defeat Japan, it wasn’t without considerable fiction and infighting as commanders within the independent, powerful commands competed for the same resources and the attention of senior leadership.

Given the dynamics of the post-war geopolitical environment, a global military presence was viewed as a guarantee against Communist expansion. Achieving such presence necessitated an effective, geographically-focused, long-term, joint-command arrangement. Between this and the lessons learned from the Second World War, legislation over the course of three decades established geographic unified commands, clarified lines of command for unified commanders, and, per the Goldwater-Nichols Department of Defense Reorganization Act of 1986, permanently assigned forces to unified combatant commands.

The premise and purpose of Combatant Commands remains essentially the same today. Combatant commanders integrate and utilize air, land, sea, and amphibious forces within the geographic or functional area of their control to achieve U.S. national security objectives. They are responsible for accomplishing missions assigned to their region, designating objectives, assigning tasks, and giving authoritative direction over all aspects of military operations as well as all aspects of joint-training and logistics. Likewise, they are responsible for establishing command relationships with subordinate commands and for organizing subordinate units as deemed necessary. They take direction from the Commander in Chief – the President – and are responsible to the Secretary of Defense.

Combatant commands offer several benefits. First, and perhaps most importantly, they provide unified and integrated command and control of cross-service forces in a theater. This is critical for the United States’ current military doctrines, which emphasis use of joint-service application of force. By minimizing confusion, competition, and conflict between the services in operations, the military can more effectively conduct its primary mission of keeping America secure and waging conflict. For functional combatant commands, integrating all elements of a particular warfighting domain – such as cyber, space, and strategic forces – under a single chain of command allows for easier oversight, coordination, and rapidity of action.

Second, as regional combatant commanders wield considerable influence over American foreign policy in their area of responsibility and have the resources and authority to act quickly, they can be disproportionately effective, compared to other American foreign policy actors, in shaping dialogue and events in theater so as to advance American security and foreign policy interests. Likewise, their relationships and integration with regional counterparts through military engagement programs provides them policy leverage that other elements of the U.S. foreign policy apparatus may not possess. Frequently, the power to “get something done” may lie with a foreign military rather than in a foreign ministry. As such, the United States’ government has increasingly deferred to and provided resources for combatant commanders to achieve regional objectives, regardless of whether those objectives are distinctly military in nature or not.

Combatant commands also come with challenges both inherent to their structure and manifest from their historical and contemporary execution. First is manifest from the policy influence that combatant commanders have. Commentators have suggested that combatant commanders have overstepped their bounds in executing American foreign policy. The resources of the DoD and combatant commands may provide a quick response to a foreign issue, but not necessarily the correct or most effective response. Once combatant commands are engaged in a foreign policy effort, they tend to continue, as it is difficult and time consuming to transfer responsibilities to civil organizations. Because of this, civilian agencies that are, by law and by tradition, supposed to manage U.S. foreign relations have tended to be relegated to an increasingly secondary role – and have faced budgetary pressures reflecting that. Similarly, the influence of combatant commanders and their role in executing U.S. foreign policy raises questions about the civilian oversight and control.

This issue ultimately comes down to a key point bout handling the issues of today’s world. Military engagement programs with other countries can be seen only as part of the overall engagement activity of the U. S. government. Modern security challenges such as terrorism, narcotics, smuggling, and international criminal networks can no longer be managed as single agency programs but must be integrated into “whole of government” programs. That combatant commands and their commanders have widened, not closed, the gap between the foreign policy agencies involved in a “whole of government” approach is a distinct challenge and concern.

Next, the geographically organized and regionally focused combatant command structure does not readily accommodate solutions to post-Cold War era challenges such as the emergence of transnational groups and regional powers, which operate outside traditional borders and in nontraditional domains. Strict geographic regionalism is no longer how the world operates. From this stems issues of and disagreement over responsibility over problems that extend across areas of command. Coordination on handling these new and emerging challenges will be increasingly difficult if the rigidity of the combatant command structure is maintained. Meanwhile, the lead for two major security concerns of priority today – international terrorism and the proliferation of weapons of mass destruction – falls squarely on the shoulders of two functional combatant commands – Special Operations command and Strategic Command, respectively. The geographic combatant commands are, by their nature, not designated as the lead organizations for managing two of the United States’ primary military challenges.

Considering these challenges, experts both within and outside the Department of Defense have offered several suggestions for reform of the combatant command structure – or fundamental change to the way the United States organizes command and control. Nonetheless, in the present day, combatant commands play a vital role within the United States’ military and defense policy, and their commanders are actors of considerable influence for American foreign policy. The combatant command structure has brought the United States considerable military advantage throughout the past decades – even if it comes with drawbacks and faces increasingly difficult questions and issues.