Observations on Global Military Posture


The secretary of defense has outsized influence over America’s global network of bases, the number of military personnel stationed overseas, and the frequency of international visits, exercises, and rotational deployments of forces stationed in the United States—in short, the worldwide posture of the U.S. military.

Along with helping the president decide when, where, and how to use military force and ensuring our military has the resources to properly train and equip itself for war, maintaining the Department of Defense’s global posture belongs among any secretary’s top priorities.

This network of bases has for many decades generated significant advantages for the United States.  But these advantages are not static, and the systems and assumptions that enable them are complex. Serious changes can take decades of investment in both relationships and facilities, and minor details can have major implications on size and readiness of the U.S. military.  The next secretary of defense would do well to see defense posture as more than an extensive map of real estate agreements and instead devote time to understanding and refining this global system.

There are a few interrelated characteristics of the American way of war that help to illustrate why global posture is so important.

First, the United States fights far away from home. The United States enjoys favorable geography. Two oceans and no major hemispheric threats have enabled the United States to focus on building an international system that is beneficial to our global interests. But this means that projecting transoceanic power, certainly if long-duration in nature, requires a vast network of ports, airfields, and bases from which to operate and sustain operations, as well as the political agreements to ensure access. The U.S. military operates across a spectrum of overseas presence. This spectrum ranges from permanent bases for large U.S. military units, to bases with a small permanent U.S. presence that can scale up quickly if needed, and to bases that have no permanent U.S. personnel but can accommodate them for contingencies or security cooperation activities. Some of these are located in U.S. sovereign territory (e.g., Guam), but the vast majority overseas are provided by our allies and partners via treaty obligation or access agreements.

Second, the United States almost always fights alongside allies and partners. American strategy since the end of World War II has depended on sustaining a network of alliances and key partnerships that, among many other benefits, typically ensure when U.S. forces are sent into battle, that they fight alongside militaries from from other nations. Having U.S. forces deployed forward in peacetime typically means that multinational exercises, training courses, and unit-level exchanges are commonplace and help facilitate interoperability and coalition warfighting effectiveness.

Third, U.S. strategy depends on deterring adversaries. The United States is largely a status quo power — meaning that our national security strategy focuses mainly on sustaining a healthy international system. Maintaining that status quo requires that U.S. military forces maintain a degree of presence in areas where doing so is an important part of the strategic balance. The deterrence equation is a complex one, but rarely can the United States take the overseas military presence variable to zero and credibly maintain strategic balance. Doing so would require the United States to convince adversaries that it would quickly deploy military forces from their U.S. bases to address even the most minor regional security tensions.

A few arguments have emerged in recent years that have challenged the decades-long consensus on the above three points and the next secretary of defense would do well to understand and be prepared to respond to them immediately.

Argument: The Uncertain Security Environment Defies the Predictability Overseas Posture Requires. This argument advances the notion that since the global security environment is somehow uniquely uncertain and complex, the Pentagon cannot predict with a reasonable degree of certainty where in the world it may be asked to engage in military operations. This case is frequently presented by senior policymakers in reports, speeches, and Congressional testimony. While we doubt that any senior defense official using this argument links it to a desire to gut America’s overseas defense posture, this line of reasoning – including a question of whether U.S. overseas basing is itself a cause of instability – is absolutely employed by others in the Pentagon and on Capitol Hill to help justify doing exactly that.

But the fact of the matter is we absolutely can predict with a reasonable degree of certainty the regions of the world where U.S. forces are most likely to engage in combat operations, as dictated by both international trends and U.S. interests. The so-called “arc of instability” from North Africa across the Middle East to the Persian Gulf  and beyond is and has been the main theater of military engagement in recent years. As Andrew Bacevich points out:

From the end of World War II to 1980, virtually no American soldiers were killed in action while serving in [the Middle East]… Since 1990, virtually no American soldiers have been killed in action anywhere except in the Greater Middle East.

Beyond the Middle East, core U.S. national interests depend on maintaining favorable balances of military power in Europe and Asia. Though the nature of those commitments can and should change to reflect the balance of opportunities and challenges, the overall demands are fairly certain. But for many, the conventional wisdom is this: the world is more complex and uncertain than the Cold War. Ergo, the argument goes, consolidating military forces in the United States can better enable global expeditionary operations — never mind the requirements of distance or the increased demand for crisis response forces. A version of this argument helped carry the day in recent Pentagon debates over whether to maintain the several U.S. Army brigades in Europe.

Argument: Overseas Presence is Costlier than Consolidating U.S. Forces at Home. Often in debates about posture, the cost of maintaining U.S. military bases and forward-stationed units is highlighted and the perceived efficiencies with bringing units back to bases in the United States is looked on favorably. While apples-to-apples comparisons are hard to come by, it is probably the case that, absent any other factors, maintaining, say, an Army brigade at a sprawling base in the United States is cheaper than sustaining that same unit overseas. But other important variables come to play. First is the cost sharing by allies and partners, who typically foot at least part of the bill —  indeed, the agreements the United States has negotiated with countries such as Germany, Japan, and South Korea are advantageous.   More important is the cost of replacing that steady-state presence with something else. Often the Department of Defense will reduce permanent presence overseas with what it calls “rotational presence.” That rotational presence is often quite costly, and in some cases likely comes very close to the cost of maintaining a permanent presence (the best recent analysis of this can be found in a 2013 RAND report). Depending on the rotation frequency or unit type, it can actually demand a baseline of far more forces at higher cost. A poorly kept secret in Pentagon force planning arguments, shifting to a rotational base to support the rotational presence is often a driver for adding force structure (an equation that has not gone unnoticed by services under Budget Control Act caps)—further increasing the financial burden. On balance we find that arguments for reducing overseas military presence based on cost alone to be unpersuasive and superficial—but in the often zero-sum fiscal environment inside the Pentagon and on Capitol Hill, these arguments can carry the day.

The result of these arguments and others (e.g., the desire of Congressional delegations to preserve bases and infrastructure in their districts) has led, we believe, to a global posture network unlikely to be an adequate enabler of U.S. military operations. This network will not be easy to improve. The United States does not simply walk into an overseas base or build necessary facilities overnight. Further, it will require senior leader time and attention to ensure enabling agreements are favorable to U.S. military requirements for training and operations. For instance, the recent progress in increasing U.S. military access in the Philippines was the product of nearly 7 years of quiet negotiations.

We believe the next secretary of defense ought to initiate a comprehensive review of U.S. military global posture. It has been over a decade since the last major U.S. defense posture review recommended significant reductions to U.S. overseas basing. The years since have included additional reductions to overseas bases, most notably reductions in U.S. Army brigades stationed in Germany. There have been other posture changes of note over the last decade that point to the necessity of such a review: in Europe, the addition of missile defense forces, crisis response forces, and increased rotational presence aimed at deterring Russia; in Asia, more robust forward-stationing and rotational presence, such as U.S. Marines in Darwin; Littoral Combat Ships in Singapore, etc. Such a review should fully capture the impact that a changing security environment (e.g., a more aggressive Russia; a more assertive China; the increasingly dispersed ISIS threat, the increased awareness of threats to U.S. embassies, etc.) and operational environment (e.g., the proliferation of precision munitions and so-called Anti-Access/Area-Denial networks) is having on U.S. global defense strategy.

We recommend the review start this year and be completed in time to shape the FY2019 DOD budget submission to Congress (so, February 2018). Such a review should be global in scope, resource informed, and also include domestic bases and infrastructure that are critical components and cost-drivers. The important tradeoffs between presence and warfighting (as Michael Mazarr cogently described in his recent piece) are critical to capture and frame as part of that review.

The U.S. military requires overseas bases and infrastructure to fight and win wars and to deter them from happening in the first place. No amount of technology or rapid global strike capabilities will be able to fully substitute for forward-stationed U.S. forces capable of “fighting tonight.” A comprehensive update of America’s overseas military presence would be an important and useful contribution to the debate about U.S. defense strategy and spending.


Shawn Brimley is the Executive Vice President and Director of Studies at the Center for a New American Security. Mr. Brimley served in the Pentagon as Special Advisor to the Under Secretary of Defense for Policy and at the White House as Director for Strategic Planning on the National Security Council staff.

Loren DeJonge Schulman is the Deputy Director of Studies and Leon E. Panetta Senior Fellow at the Center for a New American Security. Ms. Schulman left the White House in 2014 after serving as Senior Advisor to National Security Advisor Susan Rice. She has also worked as Chief of Staff to the Assistant Secretary of Defense for International Security Affairs, Director for Defense Policy and Strategy on the National Security Council Staff, and as a special assistant to Secretary of Defense Robert Gates.

Image: U.S. Air Force photo by Staff Sgt. Efren Lopez