Defense Primer: Geography, Strategy, and U.S. Force Design

Defense Primer: Geography, Strategy, and U.S. Force Design

Defense Primer: Geography, Strategy, and U.S. Force Design

Updated July 7, 2025 (IF10485)

World Geography and U.S. Strategy

World geography is an influence on U.S. strategy, which in turn helps shape the design of U.S. military forces. Most of the world's people, resources, and economic activity are located not in the Western Hemisphere, but in the other hemisphere, particularly Eurasia. In response to this basic feature of world geography, U.S. policymakers starting in the 1940s chose to pursue, as a key element of U.S. national strategy, a goal of preventing the emergence of regional hegemons in Eurasia. This objective reflected a U.S. perspective on geopolitics and grand strategy developed by U.S. strategists and policymakers during and in the years immediately after World War II that incorporated two key judgments:

that given the amount of people, resources, and economic activity in Eurasia, a regional hegemon in Eurasia would represent a concentration of power large enough to be able to threaten vital U.S. interests; and

that Eurasia is not dependably self-regulating in terms of preventing the emergence of regional hegemons, meaning that the countries of Eurasia cannot be counted on to be fully able to prevent, through their own choices and actions, the emergence of regional hegemons, and may need assistance from one or more countries outside Eurasia to be able to do this dependably.

Preventing the emergence of regional hegemons in Eurasia is sometimes also referred to as preserving a division of power in Eurasia, or as preventing key regions in Eurasia from coming under the domination of a single power, or as preventing the emergence of a spheres-of-influence world, which could be a consequence of the emergence of one or more regional hegemons in Eurasia. Although U.S. policymakers have not often stated explicitly in public the goal of preventing the emergence of regional hegemons in Eurasia, U.S. military operations in World War I and World War II, as well as numerous U.S. military wartime and day-to-day operations since World War II (and nonmilitary elements of U.S. national strategy since World War II), appear to have been carried out in no small part in support of this goal.

U.S. Strategy and Force Design

The goal of preventing the emergence of regional hegemons in Eurasia is a major reason why the U.S. military is structured with force elements that enable it to deploy from the United States, cross broad expanses of ocean and air space, and then conduct sustained, large-scale military operations upon arrival in Eurasia or the waters and airspace surrounding Eurasia. Force elements associated with this objective include, among other things

An Air Force with significant numbers of long-range bombers, long-range surveillance aircraft, and aerial refueling tankers.

A Navy with significant numbers of aircraft carriers, nuclear-powered (as opposed to non-nuclear-powered) attack submarines, large surface combatants, large amphibious ships, and underway replenishment ships.

Significant numbers of long-range Air Force airlift aircraft and Military Sealift Command sealift ships for transporting ground forces personnel and their equipment and supplies rapidly over long distances.

Consistent with a goal of being able to conduct sustained, large-scale military operations in Eurasia or the oceans and airspace surrounding Eurasia, the United States also stations significant numbers of forces and supplies in forward locations in Europe, the Indo-Pacific, and the Persian Gulf.

Comparing U.S. Forces to Other Countries' Forces

The United States is the only country in the world that designs its military to be able to depart one hemisphere, cross broad expanses of ocean and air space, and then conduct sustained, large-scale military operations upon arrival in another hemisphere. The other countries in the Western Hemisphere do not design their forces to do this because they cannot afford to, and because the United States is, in effect, doing it for them. Countries in the other hemisphere do not design their forces to do this for the very basic reason that they are already in the other hemisphere, and consequently instead spend their defense money primarily on forces that are tailored largely for influencing events in their own local regions of that hemisphere. (Some countries, such as Russia, China, the United Kingdom, and France, have an ability to deploy forces to distant locations, but only on a much smaller scale.)

The fact that the United States designs its military to do something that other countries do not design their forces to do can be important to keep in mind when comparing the U.S. military to the militaries of other nations. For example, the U.S. Navy has 11 aircraft carriers while other countries have no more than one or two. Other countries do not need a significant number of aircraft carriers because, unlike the United States, they are not designing their forces to cross broad expanses of ocean and air space and then conduct sustained, large-scale military aircraft operations upon arrival in distant locations. As another example, it is sometimes noted that U.S. naval forces are equal in tonnage to the next several navies combined, and that most of those several navies are the navies of U.S. allies. Those other fleets, however, are mostly of Eurasian countries, which do not design their forces to cross to the other side of the world and then conduct sustained, large-scale military operations upon arrival in distant locations. The fact that the U.S. Navy is much bigger than allied navies does not necessarily prove that U.S. naval forces are either sufficient or excessive; it simply reflects the differing and generally more limited needs that U.S. allies have for naval forces. (It might also reflect an underinvestment by some of those allies to meet even their more limited naval needs.)

Measuring the Sufficiency of U.S. Forces

Countries have differing needs for military forces. The United States, as a country located in the Western Hemisphere with a goal of preventing the emergence of regional hegemons in Eurasia, has defined a need for military forces that is quite different from the needs of countries that are located in Eurasia. The sufficiency of U.S. military forces consequently is best assessed not through comparison to the militaries of other countries (something that is done quite frequently), but against U.S. strategic goals, which in turn reflect U.S. policymaker judgments about the United States' role in the world.

Force-Planning Standard

The geography of Eurasia itself is a factor in U.S. force design in relation to the force-planning standard, meaning the number and types of simultaneous or overlapping conflicts or other contingencies that the U.S. military should be sized to be able to conduct—a planning factor that can strongly impact the size of the U.S. defense budget. (Other terms for referring to the force-planning standard use force-sizing instead of force-planning, and construct or metric instead of standard.) Eurasia includes three regions that since the 1940s have been of particular interest to U.S. policymakers and military force planners—East Asia (where potential adversaries include China and North Korea), Southwest Asia (which includes potential adversaries such as Iran), and Europe (where the potential adversary is Russia). The question is what force-planning standard to adopt, given U.S. interests in these three regions of Eurasia.

Following the end of the Cold War, U.S. military forces were sized to be able to fight and win two overlapping major regional conflicts or major regional contingencies (MRCs). In subsequent years, the U.S. force-planning standard was reduced to what was referred to as a win-hold standard, meaning an ability to fight and win one MRC while conducting a holding action in a second MRC. Under the win-hold standard, the United States, after winning the first MRC, would redeploy forces from the first MRC to augment those already involved in the second MRC. The Biden Administration's 2022 National Defense Strategy document (see box below) stated that U.S. forces are to be sized to be able to prevail in one all-domain conflict while having additional capabilities to contribute to deterring a second major conflict and "to respond to small-scale, short-duration crises without substantially impairing high-end warfighting readiness, and to conduct campaigning activities [i.e., ongoing day-to-day activities] that improve our position and reinforce deterrence while limiting or disrupting competitor activities that seriously affect U.S. interests."

Great power competition with China and Russia has prompted some observers to ask whether the force-planning standard should be changed to being able to fight two simultaneous or overlapping major conflicts—a so-called two-war or two-major-war standard—or some other construct for engaging in multiple simultaneous or overlapping major conflicts.

Indo-Pacific Compared to Europe

For the U.S. military, the Indo-Pacific is viewed as more of a maritime and aerospace theater of operations, meaning a theater where naval forces (i.e., the Navy and Marine Corps) and the Air Force are more predominant, while Europe is viewed as more of a continental or land-oriented theater of operations, meaning a theater where the Army and the Air Force are more predominant. A choice by U.S. policymakers to put more emphasis on one of these theaters than the other can thus affect the composition of U.S. military forces.

Strategy Is a Policy Choice, Force Design Is a Consequence

That U.S. policymakers starting in the 1940s chose to pursue a goal of preventing the emergence of regional hegemons in Eurasia does not necessarily mean this goal was a correct one for the United States to pursue, or that it would be a correct one for the United States to pursue in the future. Whether it would be a correct one for the United States to pursue in the future would depend on policymaker views regarding the two key judgments outlined earlier. A decision on whether to continue pursuing such a goal would then influence U.S. military force design for the future. A change in U.S. foreign policy, the U.S. role in the world, and U.S. grand strategy toward one that accepts or supports the emergence of a spheres-of-influence world with spheres led by countries such as Russia, China, and the United States (whose sphere would likely be centered on the Western Hemisphere) could lead to a change in the U.S. force-planning standard, the size and composition of U.S. military forces, and U.S. defense plans, programs, and budgets.

CRS Products

CRS Report R43838, Great Power Competition: Implications for Defense—Issues for Congress, by Ronald O'Rourke.

Other Resources

White House, National Security Strategy, October 2022, 48 pp.

Department of Defense, 2022 National Defense Strategy of the United States of America, Including the 2022 Nuclear Posture Review and the 2022 Missile Defense Review, cover letter dated October 27, 2022, 80 pp.

Jane Harman, chair, et al., Commission on the National Defense Strategy, July 2024, 114 pp. (Described in the foreword as "the Commission's final report to Congress and the President.")