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1 [1] (December 8, 2025)

handle is hein.crs/govesxm0001 and id is 1 raw text is: Congressional Research Service Informing the IegisI9tive debate since 1914 S Updated December 8, 2025 Defense Primer: Geography, Strategy, and U.S. Force Design orld Geography and US. 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 beginning 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 goal reflected a U.S. perspective on geopolitics and grand strategy that incorporated two key judgments: (1) 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 (2) 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 has also sometimes been 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 may not always publicly state 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 in subsequent years, appear to have been carried out in no small part in support of this goal. The goal of preventing the emergence of regional hegemons in Eurasia is a major reason why the U.S. military has been 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. These include, among other things, (1) an Air Force with significant numbers of long- range bombers, long-range surveillance aircraft, and aerial refueling tankers, (2) 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, (3) 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, and (4) significant numbers of forces and supplies in forward locations in Europe, the Indo-Pacific, and the Persian Gulf. Cornparing U.S. Forces to Other CO tri S Forces The United States is the only country in the world that has designed 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 have not designed their forces to do this because they cannot afford to, and because the United States, in effect, has been 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 on a much smaller scale.) The fact that the United States has designed its military to do something that other countries have not designed 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 generally have no more than one or two. (China has three and is expected by some observers to eventually have a total of six or more.) 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. The fact that the U.S. Navy is much bigger than allied navies 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.) The United States has needs for military forces that are 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. Reona Dfferences and Force Design The geography of Eurasia itself is a factor in U.S. force design. 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