Analysis / Forces

Building Military Forces for the 2020s: Implementing Strategy and Exercising Global Leadership in an Era of Reduced Resources

Transition46 Series

Under the Biden administration, trade-offs among readiness, force structure, and modernization will get more difficult as the Department of Defense (DoD) budget flattens out and likely falls. Forces are likely to get smaller—perhaps much smaller in some places―and that will engender significant pushback as the services attempt to maintain global commitments and cover wartime requirements. Force design will also change as the services adapt to meet the needs of great power competition. (Note: This critical questions paper builds on the CSIS annual analysis of military forces, U.S. Military Forces in FY 2021.)

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Q1: How will the Biden administration’s strategic priorities affect force structure?

A1: The Biden administration, despite its criticism of the Trump administration’s national security policy, will likely retain many key elements of its strategy. In a 2020 Foreign Affairs article, then-candidate Joseph Biden noted that “China represents a special challenge” and that Russia seeks to undermine liberal democracy. He also cited “national security challenges from North Korea to Iran, from Syria to Afghanistan to Venezuela.” This signals continuity with both the Obama administration’s strategy and the Trump administration’s National Defense Strategy (although the new administration will be loath to admit that). 

To implement this strategy, President Biden has pledged, “the United States has the strongest military in the world, and as president, I will ensure it stays that way.” That pledge and the robust strategy are good news for force structure.

The bad news for force structure is twofold. The first is that the DoD budget will likely fall as the Biden administration focuses on domestic priorities and includes non-DoD initiatives—like climate change and global health—in a broader conception of national security. (For a detailed discussion of the prospective Biden defense budget, see the CSIS transition paper “Defense Budget Priorities for the Biden Administration.”) Second, strategists will emphasize modernization—often termed “capability”—rather than force structure—“capacity.” Many strategists propose cutting the size of forces to invest in the high-end capabilities needed for a great power conflict.The Democratic Party platform proposes retiring “legacy” platforms, as do many strategists. There is disagreement, however, about the definition of “legacy.” The military services typically interpret “legacy” as older weapons. They would retire these older weapons to buy newer versions. Strategists see “legacy” as old kinds of systems that do not meet the needs of new operational concepts. They would redesign military forces to incorporate new operational concepts and move from crewed to uncrewed aircraft. In the end, the military services are likely to win this argument since they control the money.

Q2: How will the new strategy and reduced budget affect each of the services?

A2: Army

Army force structure will likely be cut significantly as an offset for other initiatives. The strategy’s focus on China and the Western Pacific, which is mainly a naval and air theater, implies that Navy and Air Force capabilities will have priority. Although the Army has an important role to play—and has recently emphasized its activities in the Indo-Pacific region—that role is secondary.

The Army does have a primary role in any conflict with Russia. However, bringing large forces to bear in likely areas of conflict such as the Baltics and Eastern Europe is difficult. This limits the size of the force needed. Further, many strategists argue that the Europeans—far wealthier than Russia and with much larger military forces—should take the lead in such conflicts. Thus, a future conflict with Russia might drive Army modernization and force design but not its force size. 

The Obama administration planned to cut regular Army endstrength to 450,000 personnel, though the actual level never quite got there. Some discussions had proposed cuts to 420,000 or even lower. The Biden administration may resurrect such plans. Currently, the regular Army is at 486,000 and has plans to grow into the 490,000s.

If Army endstrength is squeezed as hard as many people expect, then Army redesign and modernization will slow considerably.

Air Force

The Air Force will likely cut its forces to pay for modernization. It has done this traditionally, seeking cutting-edge technology at the expense of force size. The current Air Force chief of staff, General Charles Brown, has explicitly stated his desire to do this. Over the years, the Air Force has proposed cutting the A-10, KC-10, F-16, and B-1 inventories—in some cases radically—but Congress has generally frustrated those efforts.

Because the Air Force is not buying enough new aircraft to maintain its inventory over the long term, fleet size will shrink even without accelerated retirement of “legacy” systems. Plans for a next generation air dominance aircraft indicate a continuing preference for crewed over uncrewed. Although strategists in the Biden administration may want to change this, they will likely be unable to in face of service opposition.

The Biden administration’s focus on arms control and discomfort with some elements of nuclear modernization will affect several Air Force programs. Particularly vulnerable are the long-range standoff weapon, the B61 tail kit program, and Ground-Based Strategic Deterrent (the replacement for Minuteman ICBMs).

Marine Corps

The Marine Corps has embarked on an ambitious restructuring effort, called Force Design 2030, which will orient the Corps toward maritime operations in the Western Pacific. The restructuring has been criticized for focusing too much on a maritime campaign in the Western Pacific, ignoring other global conflicts, and relying on unproven operational concepts. However, because it aligns with strategists’ focus on China, the Biden administration will likely support the concept.

To pay for this restructuring, the Marine Corps intends to shrink endstrength from 185,000 personnel to 172,000. If the DoD budget is cut, however, the force cuts might pay for the Marine Corps’ share of the budget cuts and not be available for restructuring. That would require further cuts. However, Marine Corps peacetime endstrength has been at 175,000–200,000 since the Korean War. Thus, rather than cut endstrength further, the Marine Corps will likely be forced to stretch out its restructuring plans.

Space Force

Given it would take another act of Congress to disestablish it, there is no chance that the Space Force will be eliminated, despite the recommendations of some progressive groups. However, the Space Force will remain small at under 20,000 personnel.

The Space Force will continue to develop as other programs and personnel transfer into the new service. The major decision in the next year will be how many Army, Navy, and Marine Corps space assets to incorporate. Currently, the Space Force consists only of transferred Air Force personnel and organizations.

The Biden administration might chart a new direction in space. Secretary of Defense Lloyd Austin has expressed reservations about the “pugilistic aspects” of space operations. He also referred to space as a supporting effort, not as a lead warfighter.

Special Operations Forces, Government Civilians, and Contractors

Special Operations Forces—now a separate service in all but name―will likely continue its gradual growth. Although small by U.S. standards, it is nearly as large as the British Army. One challenge will be maintaining quality as expansion continues. So far, that has not been a problem, though there have been ethical challenges. The strategic challenge will be articulating how these forces—dedicated mostly to counterterrorism and regional stability operations—can contribute to great power conflicts.

Government civilians may face a hiring freeze as part of an effort to cut costs and reduce overhead. New administrations often impose such a policy until they conduct a management review. This will be a change from the Trump administration’s increases in DoD civilian personnel. However, a Biden administration will likely cease attempts to cut benefits and will eliminate the Trump administration’s institution of “Schedule F,” which would remove civil service protections from many permanent personnel.

Contractors have become a permanent part of the federal workforce but remain controversial due to enduring questions about cost and what contractors should or should not do. 

Contractors might face some cuts because Democratic administrations favor government employees. The Obama administration had attempted “insourcing” but halted those efforts after two years, having failed to produce savings and received criticism for increasing the visible size of government. A Biden administration might try the same approach but will end up with the same result. Long-term, contractors will continue to be a significant element of infrastructure activities in the United States and operations overseas because of their generally lower cost, greater flexibility, and reduced visibility.

Q3: What about the 350 (or 500) ship Navy?

A3: The Navy is a special case both because it will likely receive high priority in a Biden strategy and because of the many recent proposals regarding its structure. President Donald Trump had set a goal of 355 ships, but the Navy could not develop an affordable plan that met this goal. DoD published a shipbuilding plan at the end of the Trump administration that called for 500 ships, crewed and uncrewed, but the plan required large increases in the shipbuilding budget. Secretary Austin has stated his intention to review the Navy shipbuilding plan. 

The Biden administration will almost certainly cut the target fleet size, probably to something in the 320s, because of concerns about affordability. (Currently, the fleet size is about 300.) However, the major fleet elements will continue. The fleet will include uncrewed surface and undersea systems because these have broad support as innovative technologies. It will build attack submarines, much favored by strategists because of their covert capabilities, at a consistent rate of two per year, but not reach the three per year rate that the DoD plan had called for because of the high cost. The Navy will continue construction of destroyers at about the current rate of two per year and fund both the new frigate program and the new light amphibious warship. All three initiatives have bipartisan support. To save money, the plan will call for retiring older ships like the CG-47 class cruisers and early versions of the Littoral Combat Ships.

Two major uncertainties are aircraft carriers and uncrewed aircraft. Former secretary Mark Esper had implied a reduction in the number of large nuclear carriers in favor of smaller carriers. The last shipbuilding plan showed no such change. Strategists have long argued to cut back on aircraft carriers because of their high cost and vulnerability in great power conflicts, but the imperatives of maintaining the industrial base and continuing day-to-day crisis response have pushed Congress to maintain higher carrier force levels. 

The controversy about uncrewed aircraft centers on function. The Navy is developing the MQ-25 for refueling missions whereas many strategists want the aircraft developed for strike missions.

Q4: Will everyone be happy with the force structure changes?

A4: Of course not. On the left, progressives will want deeper budget cuts and, therefore, smaller forces. Libertarians will want more restraint in foreign policy objectives and smaller forces that are based primarily at home. Defense hawks will want higher budgets and larger forces, or at least fewer force cuts. Many strategists will want more rapid restructuring for great power competition.

The key tension for force structure will be between the desire to cut size to invest in modernization and the need to maintain day-to-day deployments for crisis response, ongoing operations, and allied and partner engagement. If the forces get too small, then the operational tempo required to maintain these deployments will stress personnel. This would hurt sustainability of the all-volunteer force, particularly if the economy recovers and recruiting and retention get more challenging as a result of competition for labor. The Biden administration, like every administration before it, will pledge to support service members, so it will need to heed complaints about stress.

To get out of this dilemma, the Trump administration in its NDS proposed prioritizing deployments through a process called Dynamic Force Employment. However, the press of overseas events prevented any significant reduction in the level of deployments.

The Biden administration will be particularly conflicted here because of its often-stated desire to reassert U.S. global leadership. The United States cannot be a global leader if it pulls its forces back from global deployments. Some strategists have argued that a “virtual” or intermittent presence from the United States can substitute for forward stationing or continuous rotations. However, critics point out that virtual presence is actual absence. Knowing that a carrier is in Norfolk does not have the same impact as seeing 90,000 tons sail into one’s harbor.

Q5: How should the Biden administration structure military forces?

A5: The best course for Biden’s DoD will be to pursue a strategy that implements a high-low mix, increases reliance on reserve forces, and promotes a gradual transition toward new kinds of technologies that can meet strategic needs at lower cost, though with some risk.

A high-low mix recognizes that there is not enough money to equip all forces with expensive, high-end systems and still retain enough size to meet global deployment commitments. Thus, the high end of the force should be equipped with new systems like stealth (though not in the numbers desired). 

The low end of the mix would extend the life of older systems and upgrade their capabilities to have the numbers needed for global commitments and warfighting depth. The “low end” systems would still overmatch most militaries of the world other than Russia and China. It could take on regional adversaries like North Korea or Iran or participate in follow-on operations in great power conflicts after initial attrition of the high-end forces.

Uncrewed systems can constitute the low end in many warfighting situations but are unsuitable for most day-to-day deployments. Such systems cannot do the peacekeeping, presence, training of partners and allies, evacuations of U.S. citizens, or humanitarian relief missions that are expected of deployed forces.

More reliance on reserve forces provides a hedge against a conflict that is larger or longer than a smaller active force can sustain. The scale of great power conflict is often hard to imagine after the regional wars of the last half-century. Further, military planners typically envision short wars, but the reality is often much longer than these plans allow for. Reserve forces provide the depth needed. The risk is in timing since reserve units take longer to deploy than active-duty forces. Reserve forces are also less useful for day-to-day deployments.

Gradual transition to uncrewed systems would put limited numbers of these new technologies into the field quickly, see how they work, and then have them replace existing platforms at a steady rate as those older platforms reach the end of their service lives. That means dialing back on the older systems as new systems show their value rather than trying to make an abrupt shift. 

The Navy’s experience with aircraft carriers is a lesson in how not to make the shift. The Navy has sought to retire existing carriers early, even while continuing to build new carriers. This is extraordinarily expensive and has failed because Congress forces the Navy to operate existing carriers to their full service lives. Instead, the Navy should move toward slower carrier construction―one every eight years rather than one every five years―and let the carrier fleet decline gradually. Slower construction would free up funds to invest in new technologies while not causing a major disruption of the shipbuilding industrial base and allowing a hedge for the future should shipbuilding plans change.

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(Photo Credit: DoD photo by Lisa Ferdinando. The appearance of U.S. Department of Defense (DoD) visual information does not imply or constitute DoD endorsement.)

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