The perennial debate about whether U.S. allies are contributing sufficiently to the collective defense of the post–World War II liberal international order has resurfaced in recent years. In this report, RAND researchers describe the Burdensharing Index that they constructed to aid in measuring and analyzing allied contributions.

Burdensharing and Its Discontents

Understanding and Optimizing Allied Contributions to the Collective Defense

King Mallory, Gene Germanovich, Jonathan W. Welburn, Troy D. Smith

ResearchPublished May 7, 2024

New security challenges from Russia, China, North Korea, and Iran have reignited the perennial debate about whether U.S. allies in the North Atlantic Treaty Organization (NATO) and in Asia are contributing sufficiently to the collective defense of the post–World War II liberal international order. The debate, which had subsided after the Cold War ended, has once again become a high priority in the U.S. foreign policy agenda. However, the traditional standard for measuring allied contributions — military expenditures as a percentage of gross domestic product (GDP) — provides an incomplete analytic foundation for understanding burdensharing. At the request of the Office of the Secretary of Defense, RAND researchers reviewed the burdensharing debates and the associated literature and constructed a Burdensharing Index to aid in measurement and analysis. The index provides a more sophisticated picture of allied burdensharing than is possible when focusing solely on military spending as a percentage of GDP. The index also helps policymakers understand how they might incentivize additional allied commitments to generating the capabilities required for potential warfights, as identified in the 2018 National Defense Strategy (NDS). Although the U.S. share of the costs of collective defense in Europe and Asia is certainly disproportionate, the U.S. burden is not as lopsided as some have asserted. As estimated by the Burdensharing Index presented in this report, the United States bears slightly less than half (about 47 percent) of the total burden of providing the collective defense.

Key Findings

The Burdensharing Index shows that the U.S. share of the burden is not as lopsided as some claim

  • As constructed, the Burdensharing Index gives a rough indication of the efficiency with which each ally converts the inputs that it contributes to the collective defense (e.g., spending on military equipment) into outputs that contribute to military preparedness and overseas deployments (e.g., strategic airlift). The index also allows for the comparison of each ally's percentage contribution to the total burden of the collective defense with its share of total allied GDP.
  • Although the U.S. share of the costs of collective defense in Europe and Asia is certainly disproportionate, the U.S. burden is not as lopsided as some have asserted. As estimated by the Burdensharing Index presented in this report, the United States bears slightly less than half (about 47 percent) of the total burden of providing the collective defense.
  • The NATO and Asian allies supply a greater share of total allied personnel and ground forces than the United States does. The United States supplies a greater share of total allied air forces, naval forces, and intelligence assets.

Policymakers can use the index to identify the best candidates to make investments in needed capabilities

  • The researchers use results from the Burdensharing Index to compare supply (what allies already contribute in military inputs and outputs) and demand (what more the United States desires from allies, particularly investment in the capabilities required to succeed in the potential warfights identified in the 2018 NDS). This allows policymakers to see which capabilities are most needed and which allies are the best candidates to make investments in those capabilities.
  • The authors identify five approaches that might elicit greater allied contributions to the collective defense: update alliance treaties and associated architecture, unbundle the collective defense good (to exploit excludability and rivalry), use assurance contracts, benchmark allied performance, and segment allied defense contractors.

Recommendations

  • The U.S. Department of Defense should systemize the Burdensharing Index methodology presented here to develop an analytically informed, policy-relevant, and enduring approach for incentivizing greater allied contributions.
  • The Department should populate the index with data biennially to provide an improved basis on which to formulate policies toward key allies. This effort should include such tasks as administering a survey on expected allied combat proficiency (presented in the report), constructing freedom-of-movement measures for the Pacific theater, and gathering longitudinal data that would allow the analysis of historical trends.

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Document Details

  • Copyright: RAND Corporation
  • Availability: Available
  • Year: 2024
  • Print Format: Paperback
  • Paperback Pages: 152
  • Paperback Price: $49.95
  • Paperback ISBN/EAN: 1-9774-1326-9
  • DOI: https://doi.org/10.7249/RR4189.1
  • Document Number: RR-4189/1-OSD

Citation

RAND Style Manual
Mallory, King, Gene Germanovich, Jonathan W. Welburn, and Troy D. Smith, Burdensharing and Its Discontents: Understanding and Optimizing Allied Contributions to the Collective Defense, RAND Corporation, RR-4189/1-OSD, 2024. As of September 11, 2024: https://www.rand.org/pubs/research_reports/RR4189z1.html
Chicago Manual of Style
Mallory, King, Gene Germanovich, Jonathan W. Welburn, and Troy D. Smith, Burdensharing and Its Discontents: Understanding and Optimizing Allied Contributions to the Collective Defense. Santa Monica, CA: RAND Corporation, 2024. https://www.rand.org/pubs/research_reports/RR4189z1.html. Also available in print form.
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This research was sponsored by the Office of the Secretary of Defense and conducted within the International Security and Defense Policy Program of the RAND National Security Research Division (NSRD).

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