An American Force Structure for the 21st Century

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The United States is unprepared for its current strategic challenges. Since the end of the Cold War, no nation could seriously threaten the territorial or political integrity of America or its allies. But that has changed, and U.S. policymakers now consider the United States to be engaged in strategic competition with the People’s Republic of China, which is developing its military to contest the United States for dominance in the Western Pacific and beyond. In addition, Russia has revitalized and modernized enough of its military to pose a threat on NATO’s eastern flank and has also demonstrated a willingness to take territory from neighboring nations.

While the United States maintains global security responsibilities, much of its combat power — along with its sustainment base — is located in the homeland and would require transportation into theater in the event of war. The requirement to deploy globally in a crisis or conflict is not new. But the challenges in executing such movement rapidly enough to be relevant are novel ones. Influenced by the successes of Desert Storm, the U.S. national security leadership fashioned the nation’s military for short wars that would quickly deny U.S. adversaries their objectives. America’s military leadership also has had the luxury of being able to plan for a protracted logistics build-up. In the future, the country’s most powerful potential adversaries start with significant advantages that render a strategy focused on rapid denial of their objectives risky.



Managing this new strategic reality will require America’s leaders to rethink the nation’s approach to defense, and not just in terms of new warfighting capabilities — such as for space and cyberspace — but also in terms of the balance between fighting and supporting forces. The U.S. military does not have enough logistics capability to rapidly deploy for and sustain a fight against a peer-level adversary. But the magnitude of the imbalance, and the fact that the U.S. defense budget is very unlikely to grow enough to address the imbalance while continuing to fund current combat capabilities, requires recognizing a very difficult truth. To enable the United States to prevail in a fight against a peer-level adversary oceans away — and in a potentially protracted contest — requires shifting a large portion of the defense budget from combat capabilities to deployability and sustainment assets. Only by having the supporting and sustainment capabilities to succeed in such a conflict can the United States maximize its ability to deter any such conflict in the first place.

The United States Has Been Here Before 

The U.S. Navy has global power projection capabilities, but it is vulnerable in contested areas and therefore likely cannot operate for extended periods in them. To get close enough to influence the battle, the Navy will have to fight to get there, and then fight to stay there. It is faced with the same kind of dilemma that the Navy faced in World War II in terms of projecting force to actually change the behavior of Japan. The Marines can conduct short-term, small littoral operations, but lack an ability to sustain long, high-intensity combat ground campaigns. The Air Force can conduct some trans-oceanic strikes but needs theater presence to conduct a significant and sustained campaign. Moreover, aircraft are vulnerable in theater, and the Air Force cannot currently support its planes from a distance. The Army can conduct long, high-intensity combat ground campaigns if it can be deployed and sustained. But it currently lacks enough logistics structure to do this in a relevant time frame. As a result, it requires months to deploy and build a logistics base, which is a luxury it probably will not have against adversaries who will operate on rapid timelines and will work to impede U.S. operations.

While this situation is unwelcome and distressing, the United States has faced this strategic challenge before — in the period prior to Dec. 7, 1941. The United States exited World War I with the world’s largest economy and global responsibilities, even if there was no consensus about how to shoulder those responsibilities. American popular opinion in the interwar years, on balance, rejected deep engagement on the world stage. A prominent belief was that the U.S. Navy was more powerful than any potential enemy’s and could keep the country secure in its hemisphere. The nation’s Army and Army Air Corps remained small, unprepared and, except for a small force in the Philippines, was based in the United States. Once it became clear that Nazi Germany and Japan had expansionist ambitions and war clouds gathered, the United States began its tentative steps toward rearmament. Unfortunately, what was neglected in the initial rearmament was sufficient means to deploy and sustain American land-based power across oceans.

When the United States was thrust into World War II by Japan’s attack on Pearl Harbor, it lacked an ability to rapidly respond through contested lines of communications to where the fight was occurring. It could not reinforce the Philippines, an American territory that was invaded by Japan and where U.S. Army forces found themselves besieged. Nor could the U.S. military send forces to support allies defending their colonies in Africa and Southeast Asia against Axis advances.  For the next year, Germany consolidated its gains as Japan imposed dominion over most of the Western Pacific and Southeast Asia. It would take the United States nearly all of 1942 to develop the requisite power projection capacity, as well as the inter- and intra-theater sustainment capabilities, to begin the offensive land operations that would win the war.

To defeat the Axis during World War II, the United States was forced to rethink the resource balance between combat forces and the required capabilities to project and sustain those forces on the other side of the world. U.S. production comparisons help to provide an understanding of the balance.

During the course of the war, the United States built nearly six times the number of cargo ships and tankers as warships. Some of this cargo and tanker construction was to replace losses, but most were simply needed to deploy and sustain forces fighting across oceans.

Winning the war also required the production of entirely new classes of vessels suited to amphibious operations. Thousands of ocean-capable amphibious vessels were designed and constructed for forced-entry operations. These included landing-craft and tank landing ships, which were capable of extended ocean transit and direct delivery of vehicles and personnel on contested beaches. This capability was critical and provided the means to overcome the anti-access/area denial capabilities of the era. But these amphibious vessels actually spent relatively little of their time conducting forced-entry operations. Instead, they spent most of the war providing critical seaborne sustainment support and maneuver capability to ground operations, thus enabling sustained offensive operations in and across the oceans.

Sustaining land combat operations also required a change in priorities. During World War II, the United States built six times more trucks — of 1.5 tons or larger — than armored fighting vehicles. This disparity reflected the fact that consumption of all commodities in wartime was much greater than in peacetime training, and those commodities had to travel great distances between where they arrived in theater and where they were actually consumed.

The Rhyme of History: America’s Contemporary Sustainment Challenges

Today’s and tomorrow’s potential adversaries begin with a significant advantage over the United States. The 2018 National Defense Strategy identified revisionist powers, China and Russia, as America’s primary security challenge. Against these adversaries, it is likely that any kinetic conflict will occur in their regions, not in the Western Hemisphere. This will be a problem for American warfighters if the United States lacks sufficient capability to deploy and sustain forces adequate for a major war against either. Forward posture of U.S. forces is not guaranteed, and in some regions — the Western Pacific specifically — it is already problematic since potential host nations must consider the political and economic consequences of hosting U.S. forces. American bases are, moreover, vulnerable to attack from a variety of sources. As American calls for additional burden sharing by allies have suggested, significant forward posture of U.S. forces may also become increasingly unpopular politically in the United States as time goes on. Since potential adversaries will operate in their own regions, they will have the very significant advantage of time. Moreover, they will fight from interior lines, deploy and sustain from tactical and operational distances, and be shielded by anti-access/area denial capabilities located in their own territory.

World War II was, hopefully, unique in terms of its scope, scale, savagery, and destructiveness. Drawing broad and suitable lessons from it must be done with care. But considering the U.S. entry into World War II and its early challenges during that conflict suggests some potential insights relevant to today.

U.S. Military Capabilities Are Not Adequately Balanced 

America’s military capabilities today are unbalanced for the missions articulated in the National Defense Strategy. Strategic, inter-theater sealift may be inadequate for a major conflict. For the United States to deter and if need be succeed in a military conflict against a peer-level opponent, it must be able to get to the fight in an operationally relevant time with adequate force. And then it must be able to sustain those forces from the continental United States for the duration of the conflict.

America’s ability to deploy significant force in a short time is compromised by the small number of vessels available. The Military Sealift Command inventory includes about 60 cargo vessels and tankers, but most are already committed to fleet support and prepositioning. The Ready Reserve force has another 40 or so cargo and tanker vessels, but these are aging ships. In a recent “turbo activation,” the readiness of this fleet was less than 50 percent, and the ability to obtain and maintain crews over an extended period is in question. There are also another 60 ships in the Maritime Security Program. These ships are obligated to render service during wartime when called upon. But they sail commercially and are generally loaded and globally dispersed until activated for U.S. service, so their activation into military service could be delayed by weeks, if not months. Importantly, there are very few, if any, additional U.S.-flagged vessels, certainly not a sufficient number of the type required to move large amounts of military cargo. The economics of shipping simply precludes it. Unfortunately, this also means there are few mariners who are U.S. citizens, thus complicating the rapid expansion of U.S. maritime capabilities.

In addition, operations in maritime environments such as the Western Pacific are constrained by a lack of intra-theater movement capability. The United States maintains only a small, aging watercraft fleet — about 120 Army and Navy vessels — and a mere 14 expeditionary fast transports and high-speed transports for intra-theater logistics and transportation. Of these, not all are crewed, and maintenance is increasingly difficult, with new production programs being inadequate to replace the impending retirements in the current fleet. Moreover, the current watercraft fleet is globally dispersed. As a result, the United States will necessarily rely on chartered vessels for intra-theater sea-borne transport in a major contingency. This is a risky strategy since the availability of chartered vessels will depend on their own nation’s policies, the nature of the conflict, and the willingness of the crews to operate in a war zone.

While the United States does have plenty of experience chartering trucks and even railway space for intra-theater lift, it has not had similar experience with sealift. Chartering in previous conflicts has largely been a matter of activating U.S.-owned strategic sealift. Responsibilities for intra-theater logistics in maritime theaters currently remain undefined due simply to no service or command being willing to take on the role.

Unlike in the Western Pacific, the European theater will rely more on ground-based intra-theater movement. More capability in the form of Army trucking is potentially available, but most of this is in the United States and in the reserve component. It would take months to mobilize and deploy these assets. In the event of a major conflict, commercial trucking and rail will be necessary for movement from seaports to operational and tactical areas and to sustain on-going operations. As with operations in the Indo-Pacific region, reliance on commercial capabilities entails substantial risk.

The lack of strategic and especially intra-theater lift affects not only America’s ability to rapidly get into theater, but also the ability to sustain forces once deployed. Modern warfare will consume enormous quantities of munitions, fuel, spare parts, and every other class of supply.  Without continual replenishment, operations will quickly become impossible, and the survivability of deployed forces will become an issue.

Because the current strategic situation is unique in the country’s recent history — indeed, senior military and civilian leaders in the Defense Department spent their entire careers operating in a completely different context — and because the culture of the military will always favor resourcing combat capabilities, it is not surprising that America’s military is seriously unbalanced for the challenges of peer-level competition. Unfortunately, in spite of the imbalance, Pentagon and service plans continue to avoid the investment and force structure adjustments required to balance combat capabilities with the means to deploy and sustain them globally in major conflicts.

For example, the Navy plans only to replace the existing strategic sealift fleet over the next three decades and is not investing in additional intra-theater watercraft. The Army is investing only in 36 Maneuver Support Vessel-Light watercraft to replace its aging medium landing craft. But this is a tiny number for the potential needs in places like the Western Pacific, and these are small vessels that can carry only one tank apiece. Meanwhile, the Air Force is planning for dispersed operations for survivability reasons, which will further strain requirements for intra-theater lift. 

Starting the Rebalance 

Once America entered World War II, it took almost a year to enable offensive operations in combat theaters, a year that was used by the country’s enemies to make victory much costlier. A similar timeline may be in effect today, particularly if the nation’s adversaries decide to contest U.S. deployments into theater and American sustainment activities once there, as they are likely to do. This means potential peer and near-peer adversaries may not be deterred if they think they can score an easy win. And, absent a direct attack on the United States, the “easy win” may not be challenged for fear of escalation and lack of political will. Rebalancing America’s military capabilities is required if the U.S. military is to have the resources needed to be relevant to major operations against its primary potential adversaries. 

Addressing the imbalance will be a major undertaking that needs to start at the very top of the Defense Department. Clearly, the first step is to recognize the issue, and that should be done by the department’s leadership, accepted by the president, and made subject to congressional oversight and budget deliberations. Getting to this point will require realistic assessments, wargames, and simulations that account for the military, political, and diplomatic consequences of various balances between combat and supporting capabilities. As these reveal the balances that will be required in future contingencies, roles and responsibilities for managing support requirements should be established and enforced. Likewise, capabilities for force projection and theater sustainment should be moved out of the reserve component, otherwise the U.S. military will face constraints on the speed at which theaters may be opened and made ready for operations.

Once the decision to rebalance is recognized, established, and resourced, all the myriad details required for success will take substantial and ongoing attention. Perhaps attending to those details will be the most challenging aspect of all, but America’s political and military leaders should get to work now to lower the risk that history rhymes and to ensure it does not repeat.



Bruce Held joined the RAND Corporation after an Army career and directed the Forces and Logistics Program in the RAND Arroyo Center. A West Point graduate, Bruce also has an M.S. in aerospace engineering from Stanford and a law degree from the University of Maryland.

Brad Martin is a senior policy researcher and director of the Institute for Supply Chain Security at the RAND Corporation, where he has worked since November 2012. Prior to joining RAND, he served in the U.S. Navy as a surface warfare officer, retiring after 30 years of service as a captain. He has a doctorate in political science from the University of Michigan.

Image: U.S. Navy (Photo by Mass Communication Spc. 3rd Class Pat Morrissey)