Drone Substitutes: Rethinking Landpower for an America First Foreign Policy

Next Army is a collaborative series by CSIS Futures Lab and the Modern War Institute launched in honor of the U.S. Army’s 250th birthday and the Army Transformation Initiative. The commentaries explore how emerging technologies, organizational reforms, and major shifts in the strategic environment will shape the force of 2040 and beyond.

How the United States conceptualizes strategic landpower is at a crossroads. Secretary Pete Hegseth has ordered a “comprehensive transformation” of the U.S. Army, while Secretary of the Army Daniel Driscoll and General Randy George, chief of staff of the Army, have built on success in Project Convergence to accelerate change through initiatives like the Army Transformation Initiative and the Transformation in Contact initiative.

At the same time, it is increasingly clear that the U.S. national security strategy will reprioritize where and how the Army is employed. The traditional emphasis on a transatlantic security architecture with the United States as the central node in the network is giving way—despite the war in Ukraine—to a vision of the United States playing a secondary role in Europe. Furthermore, land forces, which traditionally were seen as central to projecting power in the Middle East, do not appear to be the focus of an emerging Trump, “America First,” doctrine that prioritizes economic statecraft over force posture and deal-making over security alliances. In the Pacific, landpower has become increasingly littoral power, with force structure shifting to prioritize formations like the Multi-Domain Task Force (MDTF) and air defenses better capable of generating options for warfighting and deterrence in the first island chain.

This shifting logic requires creative thinking about the types of forces the Army generates to support future contingencies based on a key economic concept: substitution. An Army built around large ground formations, which are still vital, must find ways of substituting drones for personnel and adapt to enable more modular capabilities that allow a single drone to perform multiple missions. Forward-deployed forces in large garrisons and infantry and armor-centric rotational force packages need to give way to mixed drone units that can be deployed faster and better increase partner combat power. These formations should be capable of direct support to partners and/or augmenting existing MDTFs, which include multi-domain effects, long-range fires, air defense, and brigade support battalions. Most importantly, they should be largely unmanned and capable of supporting a wide mix of intelligence, strike, and electronic attack missions critical to generating combat power in the twenty-first century.

This change requires the Army and Congress to reconsider planned cuts to larger, multi-mission systems like medium-altitude long endurance (MALE) as part of the ongoing restructuring, while experimenting with standing up new drone formations to build on ongoing Army experiments with launched effects (i.e., smaller drones launched from the ground and air). To save money and accelerate cultural change, these forces could reside in the U.S. Army Reserve and National Guard, thus lowering personnel costs and creating a model for scalability in the event of a larger-scale, protracted conflict. MALE systems have a proven track record and provide the type of standoff and multi-role capabilities a smaller force needs to support partners and allies and defend U.S. interests. At the same time, the Army will need to better coordinate with the Department of Defense (recently renamed the Department of War) and the Department of State with respect to foreign military sales. New guidance makes it easier for the United States to sell MALE systems to partners. These sales should be integrated with updated war plans and service-level modernization campaigns to ensure the optimal alignment that frees up soldiers for other missions while providing the mix of capabilities required to meet U.S. treaty requirements. That likely means selling more drones and capabilities that allow them to hunt tanks and command posts, not insurgents, while finding creative rotational packages that prioritize reserve force structure. Imagine soldiers arriving with novel sensors and payloads, essentially units combining intelligence and logistics, to help partner drones conduct armed reconnaissance along the frontline while filling the gap with smaller systems similar to those that dominate the battlefields in Ukraine.

A Flexible Frontier Force

The new defense prioritization signal is unambiguous: Europe is no longer the pacing theater for U.S. landpower, even as its security requirements persist. The America First foreign policy taking shape doesn’t imply a complete withdrawal from the world. It is not a neo-isolationist approach as much as a recalibration that shifts the focus to economic statecraft and prioritizes certain regions and concerns over others. This prioritization focuses on the homeland and countering China, not taking a leading role in guaranteeing European security.

There are mixed signals about what U.S. military forces will and won’t be pulled out of Europe. Pentagon officials have announced plans to withdraw as many as 10,000 troops from Europe, while President Trump has pledged to keep U.S. forces in Poland. Furthermore, in September, multiple Baltic states announced that they were told that U.S. funds for building partner security capacity were likely to be set to zero across Europe. These cuts don’t mean abandoning U.S. interests in Europe, which include ending the war in Ukraine. Rather, they call for new approaches that don’t rely on troop-heavy deployments and U.S. resources absent investments by partners.

At the same time, despite its battlefield setbacks in Ukraine, Russia is reconstituting. According to April 2025 testimony by General Christopher G. Cavoli, the former supreme allied commander for Europe:

According to NATO Secretary General Mark Rutte, Russia will be in a position to use military force against a NATO member state in five years. Thus, beyond Ukraine, the United States is almost certain to be confronted with an antagonistic Moscow in the future. No peace deal will change the fact that Putin has fundamentally altered the Russian economy and society, essentially creating a version of North Korea in Europe.

This presents the Trump administration and the U.S. Army, which has historically been the major instrument of U.S. military power used to secure Europe, with a dilemma. If the United States were to take an extreme position and abandon the transatlantic community, which includes its major trading partners and fellow democracies, it would leave the door open to future Russian coercion and even attacks. That is not in the United States’ interests. At the same time, if Washington ties up large amounts of military forces and resources in Europe when leaders perceive core interests in different theaters, that is also not in the United States’ interests. Those funds and formations are needed elsewhere, whether in the Americas, the Asia-Pacific, or even in U.S.-based garrisons training to wage entirely new forms of warfare envisioned by ongoing Army experiments.

Therefore, what type of force can the U.S. Army man, train, and equip that allows the Trump administration to reduce the number of soldiers in Europe without sacrificing the overall combat power needed to deter future Russian attacks? The answer lies in thinking about drones as substitutes.

In economics, substitutes refer to products that are used as alternatives to each other. Previous studies have applied the concept to study how modern states use cyber operations as low-cost alternatives to conventional forces. A military substitute is any force element, capability, or concept of employment that can replace or offset the operational effect of another force element for a given mission, in a given theater, within required time, risk, and political constraints.

Seen in this light, substituting more flexible and mobile drone formations can generate options to support U.S. interests in Europe. In place of large infantry and armored brigades, the U.S. Army can deploy MALE platforms that support forward-deployed partner forces. Imagine a drone helping conduct wide area surveillance to provide early warning of any Russian ground offensive, paired with smaller battalions, likely from the U.S. Army Reserve, fielding a wide variety of launched effects (LE). This LE battalion could support swarm attacks on any Russian advance. The MALE drones could be loaded with a mix of signal intelligence, electronic warfare, and even precision missiles to provide flexible options to strengthen NATO’s battle network and deterrence posture.

This vision of expanding the use of autonomous weapons systems is central to the Army Transformation Initiative. What hasn’t received as much attention is how best to realize this vision in the reserve forces. The U.S. Army Reserve is well-positioned to become a test ground for drone substitutes. Aviation brigades, slated for closure, in the reserve could be repurposed as a combination of drone battalions and MALE squadrons. At the same time, these units could be tested and refined rapidly by integrating them with Combat Support Training Exercises (CSTX). These readiness exercises could serve as tests—twenty-first-century Louisiana Maneuvers—on both how land forces survive on a transparent battlefield where what can be seen can be destroyed and tactics, techniques, and procedures for new drone formations.

When these systems are built with modular and open systems architectures that increase their interoperability and create the possibility of performing multiple roles and missions, they create new efficiencies. In economics, this is often referred to as the elasticity of substitution, which is how easily one input can be replaced with another in production without losing output. Applied to thinking about generating combat power, it measures how easily one capability (e.g., inputs as sensors or weapons) can be swapped with another while still producing combat power (e.g., output). If drones can be rapidly reconfigured across different payloads—say, intelligence collection, electronic warfare, and strike—with little friction, then one drone is nearly as good as another that was optimized for the task. The force is fungible in its drone platforms and highly adaptable, creating resilience against attrition and surprise.

This logic implies the U.S. Army can prioritize drone substitutes to buy down the strategic cost and risk associated with shifting defense priorities that reduce its footprint in key regions like Europe. It should keep proven MALE systems that have demonstrated an elasticity of substitution and the ability to perform multiple roles and missions. Furthermore, it should invest in new payloads to increase this elasticity and ensure no vendor sells anything that isn’t modular and open. And it means prioritizing solutions that work across multiple theaters. MALE systems can watch borders in the Americas, support maritime domain awareness missions in the Asia-Pacific, augment partner-led security missions along NATO’s flanks, and even support responding to natural disasters.

Drone substitutes won’t just change where the U.S. stations units. It has the potential to alter the grammar of deterrence. Instead of a heavy, permanently forward posture, imagine a U.S. Army capable of substituting permanent presence with multi-mission unmanned formations flowing in and out of theater. These scalable reconnaissance-strike packages take the place of expensive garrisons and, assuming they are easily deployable and modular, provide flexible options. When combined with prepositioned stocks and munitions and interoperability, they plug into allied command networks and extend sensing and reach across the front. Substitution, in this context, is the art of trading a static footprint for a dynamic web of effects—intelligence, surveillance, and reconnaissance; electronic warfare; and long‑range precision fires—that shortens the sensor‑to‑shooter timeline and enhances deterrence without committing to long-term overseas deployments and costly garrisons.

Building Elasticity into Security Architecture

The America First foreign policy will change how the U.S. Army generates landpower to uphold its NATO commitments. Changes in foreign policy always do. Massive retaliation gave way to New Look and NSC 162/2 and led the Army to focus on tactical nuclear war and new “Pentomic” formations. The end of the Vietnam War and the Nixon doctrine set the stage for the 1973 Astarita Report and new thinking that eventually led to the Active Defense and Airland Battle doctrines. The end of the Cold War created the Base Force model and led to a focus over the 1990s and into the 2000s on balancing multiple contingencies that shaped how the Army approached doctrine and modernization through efforts like Force XXI, the Army After Next, and Future Combat Systems.

Today is no different. The Army needs a deeper plan for supporting U.S. strategy. As outlined here, this plan should find cost savings based on substituting drones for personnel-heavy, forward-deployed formations. Replacing armored brigades with slightly smaller mechanized or motorized formations is unrealistic, costly, and disingenuous. But the Army can offset planned losses in Europe through drone formations that serve as force multipliers. This means the Army and Congress should reconsider some of the force cuts while accelerating aspects of ATI linked to AI, autonomous systems, and launched effects to build a force around drone substitution.

Second, any solution must be interoperable and designed to think in terms of defense policy. Even the European Union, historically reluctant to prioritize defense, has rolled out the ReArm Europe Plan/Readiness 2030. The plan calls for €800 billion in defense spending alongside large loan instruments to accelerate joint procurement across the continent and provide a regulatory framework for allowing countries a “national escape clause” so that they can use debt to finance modernization. Combined with changes to policy that make it easier to sell partners key unmanned systems, this means the Army should better coordinate with the Department of War and Department of State to create foreign military sales use cases based on the idea of drone substitution.

Third, true transformation could also extend to the reserve component. Imagine a model based on Ukraine’s approach to swarm tactics. Reserve drone units would rotate through the Baltics to certify and train while supporting NATO partners. These units could receive Federal Aviation Administration⁠–certified unmanned aircraft system training while in garrison and complete exercises, like CSTX, that accelerate their ability to directly enter regional kill chains. By reducing personnel costs and building mobilization capacity, the drone substitution strategy would contribute to deterrence.

This transformation won’t be easy. There will be upfront costs. Just as important, the U.S. Army will need to develop new ways of analyzing the cost-effectiveness of units that help the Department of War and Congress track how efficiently it is turning each U.S. tax dollar into combat power. And the Army will need authority to move money across its budget and make investments in retooling legacy MALE aircraft and adapting commercial-off-the-shelf solutions through programs like the Defense Innovation Unit’s Blue List.

Ultimately, pivoting to an Army of drone substitutes to meet the strategic moment involves considering opportunity costs and trade-offs in thinking about modern war. If the Army embraces substitution and elasticity, it can trade static garrisons for dynamic webs of unmanned effects—creating a force that is more adaptable and sustains deterrence abroad while preserving the flexibility to meet America First priorities at home and in the Pacific.

Benjamin Jensen is the director of the Futures Lab at the Center for Strategic and International Studies in Washington, D.C.