Download eBook for Free

Full Document

FormatFile SizeNotes
PDF file 5.2 MB

Use Adobe Acrobat Reader version 10 or higher for the best experience.

Research Summary

FormatFile SizeNotes
PDF file 0.1 MB

Use Adobe Acrobat Reader version 10 or higher for the best experience.


Purchase Print Copy

 Format Price
Add to Cart Paperback224 pages $49.95

Research Questions

  1. Which U.S. military actions have the desired deterrent effect?
  2. Where can efficiencies be found by adjusting the OAIs that the U.S. military undertakes for deterrence?

The United States makes significant investments in military activities that are intended to deter Russian and Iranian aggression. These investments have only grown in Europe since 2014, when Russia invaded and subsequently annexed Crimea, and remain substantial in the Middle East despite the overall trend of the United States reducing its forward posture in that theater. The increased importance of deterrence as a military mission raises the question of how the United States can most effectively and efficiently deter Russia and Iran without crowding out investments in its other key military missions — including competing with China in the Indo-Pacific.

To support defense planners in crafting effective and efficient deterrence strategies, RAND researchers conducted a multimethod analysis — consisting of a literature review, roundtables with subject-matter experts, quantitative analysis, and a case study of Ukraine — to examine conventional deterrence in two theaters: U.S. European Command (EUCOM) and U.S. Central Command (CENTCOM). Specifically, the researchers assessed the deterrent impacts of three categories of U.S. operations, activities, and investments (OAIs): U.S. forward presence; exercises and short-term deployments, such as bomber task force (BTF) missions; and security cooperation. In this report, the researchers describe their findings and offer recommendations for defense planners. This research was completed before the February 2022 Russian invasion of Ukraine. It has not been subsequently revised.

Key Findings

Forward posture is seen as an important demonstration of U.S. commitment that has a deterrent effect

  • Existing literature suggests that forward posture is important for crisis deterrence, but there are conflicting findings about its importance for general deterrence.
  • Among the OAI categories, forward posture was seen by roundtable participants as the most critical signal of U.S. commitment.
  • Basing infrastructure that enables rapid reinforcement undergirds deterrence logic in both theaters (EUCOM and CENTCOM).
  • It is unclear whether declining U.S. forward presence invites adversary aggression. Declining U.S. forward presence in EUCOM may have contributed to deterrence failure in Crimea, but how much to weight this factor is uncertain.

Exercises and short-term deployments generated conflicting findings

  • Existing literature shows that certain short-term deployments — like larger, outside-in deployments and those undertaken in the midst of a crisis — increase the chances of successful deterrence.
  • Roundtable participants saw short-term deployments and exercises as important demonstrations of capability but as less effective than forward posture for demonstrating commitment.
  • Participants viewed exercise size and complexity as more important than exercise frequency.
  • The researchers' original quantitative analysis found that short-term naval presence missions and BTF sorties do not have statistically significant effects on deterrent outcomes — and might actually increase the chances of an adversary undertaking limit-testing behavior.

Security cooperation is important for reassurance, but its deterrent effect is unclear

  • Security cooperation may have contributed to Russia limiting its aims in eastern Ukraine after Minsk II, but to what extent is uncertain.


  • Adopt more-specific ways of describing adversary actions than "malign influence." Tailored deterrence strategies require a more precise definition of the adversary actions that the United States seeks to prevent.
  • Align U.S. forward presence to reinforce clear deterrence logics. The ability to rapidly reinforce signals the denial of adversary benefits, whereas the posturing of additional strike assets signals the threat of punishment.
  • Clarify the logic of bomber task force and naval presence missions to ensure that the deployments strengthen deterrence by signaling the denial of adversary benefits or the threat of punishment.
  • Consider cost in the implementation of force employment concepts, differentiating between applications of dynamic force employment or agile combat employment that are fertile for generating efficiencies and those that generate additional requirements for which there is an opportunity cost.
  • Should resource considerations lead to a reduction in U.S. operations, activities, and investments for deterrence, be attentive to how such reductions are communicated and executed so as to reduce potential backlash from allies and partners and avoid telegraphing opportunities to adversaries.

Research conducted by

The research reported here was commissioned by then–Brig Gen Adrian Spain, Director of A5/8/9, U.S. Air Forces Europe, and conducted by the Strategy and Doctrine Program with RAND Project AIR FORCE.

This report is part of the RAND research report series. RAND reports present research findings and objective analysis that address the challenges facing the public and private sectors. All RAND reports undergo rigorous peer review to ensure high standards for research quality and objectivity.

This document and trademark(s) contained herein are protected by law. This representation of RAND intellectual property is provided for noncommercial use only. Unauthorized posting of this publication online is prohibited; linking directly to this product page is encouraged. Permission is required from RAND to reproduce, or reuse in another form, any of its research documents for commercial purposes. For information on reprint and reuse permissions, please visit

RAND is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.