Updated January 25, 2022
Defense Primer: Geography, Strategy, and U.S. Force Design
World geography is an influence on U.S. strategy, which in
U.S. Strategy and Force Design
turn helps shape the design of U.S. military forces.
The goal of preventing the emergence of regional hegemons
in Eurasia is a major reason why the U.S. military is
World Geography and U.S. Strategy
structured with force elements that enable it to deploy from
Most of the world’s people, resources, and economic
the United States, cross broad expanses of ocean and air
activity are located not in the Western Hemisphere, but in
space, and then conduct sustained, large-scale military
the other hemisphere, particularly Eurasia. In response to
operations upon arrival in Eurasia or the waters and
this basic feature of world geography, U.S. policymakers
airspace surrounding Eurasia. Force elements associated
for the last several decades have chosen to pursue, as a key
with this objective include, among other things:
element of U.S. national strategy, a goal of preventing the
emergence of regional hegemons in Eurasia. This objective
An Air Force with significant numbers of long-range
reflects a U.S. perspective on geopolitics and grand strategy
bombers, long-range surveillance aircraft, and aerial
developed by U.S. strategists and policymakers during and
refueling tankers.
in the years immediately after World War II that
incorporates two key judgments:
A Navy with significant numbers of aircraft carriers,
nuclear-powered (as opposed to non-nuclear-powered)
that given the amount of people, resources, and
attack submarines, large surface combatants, large
economic activity in Eurasia, a regional hegemon in
amphibious ships, and underway replenishment ships.
Eurasia would represent a concentration of power large
enough to be able to threaten vital U.S. interests; and
Significant numbers of long-range Air Force airlift
aircraft and Military Sealift Command sealift ships for
that Eurasia is not dependably self-regulating in terms of
transporting ground forces personnel and their
preventing the emergence of regional hegemons,
equipment and supplies rapidly over long distances.
meaning that the countries of Eurasia cannot be counted
on to be fully able to prevent, through their own choices
Consistent with a goal of being able to conduct sustained,
and actions, the emergence of regional hegemons, and
large-scale military operations in Eurasia or the oceans and
may need assistance from one or more countries outside
airspace surrounding Eurasia, the United States also stations
Eurasia to be able to do this dependably.
significant numbers of forces and supplies in forward
locations in Europe, the Indo-Pacific, and the Persian Gulf.
Preventing the emergence of regional hegemons in Eurasia
is sometimes also referred to as preserving a division of
Comparing U.S. Forces to Other
power in Eurasia, or as preventing key regions in Eurasia
Countries’ Forces
from coming under the domination of a single power, or as
The United States is the only country in the world that
preventing the emergence of a spheres-of-influence world,
designs its military to be able to depart one hemisphere,
which could be a consequence of the emergence of one or
cross broad expanses of ocean and air space, and then
more regional hegemons in Eurasia. The Biden
conduct sustained, large-scale military operations upon
Administration’s March 2021 International Security
arrival in another hemisphere. The other countries in the
Strategic Guidance document states that “at its root,
Western Hemisphere do not design their forces to do this
ensuring our national security requires us to,” among other
because they cannot afford to, and because the United
things, “promote a favorable distribution of power to deter
States is, in effect, doing it for them. Countries in the other
and prevent adversaries from directly threatening the
hemisphere do not design their forces to do this for the very
United States and our allies, inhibiting access to the global
basic reason that they are already in the other hemisphere,
commons, or dominating key regions.”
and consequently instead spend their defense money
primarily on forces that are tailored largely for influencing
Although U.S. policymakers do not often state explicitly in
events in their own local regions of that hemisphere. (Some
public the goal of preventing the emergence of regional
countries, such as Russia, China, the United Kingdom, and
hegemons in Eurasia, U.S. military operations in World
France, have an ability to deploy forces to distant locations,
War I and World War II, as well as numerous U.S. military
but only on a much smaller scale.)
wartime and day-to-day operations since World War II (and
nonmilitary elements of U.S. national strategy since World
The fact that the United States designs its military to do
War II), appear to have been carried out in no small part in
something that other countries do not design their forces to
support of this goal.
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
https://crsreports.congress.gov
Defense Primer: Geography, Strategy, and U.S. Force Design
a significant number of aircraft carriers because, unlike the
that it would be a correct one for the United States to pursue
United States, they are not designing their forces to cross
in the future. Whether it would be a correct one for the
broad expanses of ocean and air space and then conduct
United States to pursue in the future would depend on
sustained, large-scale military aircraft operations upon
policymaker views regarding the two key judgments
arrival in distant locations.
outlined earlier. A decision on whether to continue pursuing
such a goal would then influence U.S. military force design
As another example, it is sometimes noted, in assessing the
for the future.
adequacy of U.S. naval forces, 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
CRS Products
countries, which do not design their forces to cross to the
other side of the world and then conduct sustained, large-
CRS In Focus IF11798, The Interim National Security Strategic
scale military operations upon arrival in distant locations.
Guidance, by Kathleen J. McInnis
The fact that the U.S. Navy is much bigger than allied
CRS Report R43838, Renewed Great Power Competition:
navies does not necessarily prove that U.S. naval forces are
Implications for Defense—Issues for Congress, by Ronald
either sufficient or excessive; it simply reflects the differing
O'Rourke
and generally more limited needs that U.S. allies have for
CRS Report R46336, COVID-19: Potential Implications for
naval forces. (It might also reflect an underinvestment by
International Security Environment—Overview of Issues and
some of those allies to meet even their more limited naval
Further Reading for Congress, by Ronald O'Rourke and Kathleen
needs.)
J. McInnis
Measuring the Sufficiency of U.S. Forces
Countries have differing needs for military forces. The
United States, as a country located in the Western
Other Resources
Hemisphere with a goal of preventing the emergence of
White House, Interim National Security Strategic Guidance,
regional hegemons in Eurasia, has defined a need for
March 2021, 23 pp., accessed January 25, 2022, at
military forces that is quite different from the needs of
https://www.whitehouse.gov/wp-
countries that are located in Eurasia. The sufficiency of
content/uploads/2021/03/NSC-1v2.pdf.
U.S. military forces consequently is best assessed not
Department of Defense, Summary of the 2018 National Defense
through comparison to the militaries of other countries
Strategy of the United States of America, Sharpening the American
(something that is done quite frequently), but against U.S.
Military’s Competitive Edge, undated, released January 19, 2018,
strategic goals, which in turn reflect U.S. policymaker
11 pp., accessed June 9, 2021, at https://www.defense.gov/
judgments about the United States’ role in the world.
Portals/1/Documents/pubs/2018-National-Defense-Strategy-
Strategy Is a Policy Choice, Force Design
Summary.pdf.
Is a Consequence
The fact that U.S. policymakers for the last several decades
have chosen to pursue, as a key element of U.S. national
strategy, a goal of preventing the emergence of regional
Ronald O'Rourke, Specialist in Naval Affairs
hegemons in Eurasia, does not necessarily mean that this
IF10485
goal was a correct one for the United States to pursue, or
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Defense Primer: Geography, Strategy, and U.S. Force Design
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https://crsreports.congress.gov | IF10485 · VERSION 21 · UPDATED