Defense In Depth
Why U.S. Security Depends on Alliances—Now More Than Ever
Over the last several decades, the digital revolution has fundamentally transformed business best practices. The changes have been slow to penetrate the public sector, however, which remains tied to traditional thinking and practices. U.S. Secretary of State Rex Tillerson is trying to review all aspects of the State Department to get it up to speed, which is all to the good. But even bigger game would be the Pentagon, the world’s largest bureaucracy. The strategy, structure, and funding priorities of the U.S. military were set decades ago, in response to an entirely different geopolitical, economic, and technological environment.
Consider today’s elaborate and expensive network of U.S. overseas military bases, which first emerged as coaling stations for navy ships a century and a half ago. Modern surveillance and targeting technology have made the bases increasingly vulnerable, and the presence of U.S. military bases can militarize disputes and antagonize opponents that would have otherwise been more docile. U.S. bases can also encourage allies to take risks they might have avoided, thus heightening instability and entangling the United States in peripheral conflicts. Finally, forward-deployed forces are a temptation for U.S. leaders: they can make calls for intervention—even where core U.S. interests are not at stake—seem more reasonable.
As the circumstances of international politics have changed, and as innovations in technology have both shortened travel times and made in-place forces more vulnerable, the strategic and operational utility of overseas bases deserves renewed scrutiny. The three main strategic justifications for overseas bases—to deter adversaries, reassure allies, and enable rapid contingency response by the U.S. military—are no longer sufficient to justify a permanent peacetime military presence abroad.
THE DETERRENCE PROBLEM
The deterrence value of overseas military bases is frequently exaggerated. For starters, it is hard to actually demonstrate. Because success is measured by the absence of an unwanted action by an adversary, determining whether something did not happen because of deterrence, because the adversary had no intention to attack in the first place, or because of some other reason is inherently challenging.
The deterrence value of overseas military bases is frequently exaggerated.
This problem plagues many areas of U.S. foreign policy. For example, analysts such as the Brookings Institution’s Michael O’Hanlon and Richard C. Bush and policymakers alike claim that the U.S. military presence in South Korea is the only thing deterring a unilateral North Korean attack. But South Korea’s economy is 40 times the size of North Korea’s, South Korea has twice the population of North Korea, and South Korean military capabilities far exceed those of Pyongyang. These glaring gaps in economic and military power likely deter the North from attacking the South and would continue to do so even absent U.S. military power in the region.
Similarly, advocates of a forward-deployed posture in the Middle East regard the U.S. Navy’s presence in Bahrain and its daily patrolling of the Persian Gulf as the principal deterrent to Iran attempting to close the Strait of Hormuz. But Iran exports most of its oil via the strait and would impose serious economic damage on itself if it attempted to close it. Such an attempt would also threaten the vital interests of the regional powers as well as external powers that rely on the free flow of oil from the region. Iran would thus run unacceptably high risks of retaliation by an international coalition of states and would probably be deterred even without the permanent U.S. naval presence in the Gulf.
Sometimes, efforts to deter can backfire. Stationing military bases near an adversary can cause fear that generates counteraction. Russia’s actions against Georgia in 2008 and Ukraine in 2014 have been blamed on a lack of deterrence or diminished U.S. credibility, but they derive more from Moscow’s insecurities about the expansion of U.S.-led Western economic and military institutions into former Soviet republics and even up to the Russian border. Post–Cold War NATO expansion is the source of profound anxiety and lingering resentment in Moscow. Following Russian President Vladimir Putin’s annexation of Crimea, the Russian leader decried NATO expansion as an attempt at containment, and when in 2015 NATO invited Montenegro to be the newest member of the alliance, the Kremlin warned that further expansion eastward “cannot but result in retaliatory actions.” Indeed, one could say that forward deployment in some cases contributes to the insecurity it purports to prevent.
NEW TECHNOLOGICAL ADVANCES
One of the prominent arguments in favor of maintaining an indefinite U.S. military presence with such bases is that it would be too difficult and time-consuming to secure host governments’ permission for access during a crisis in which U.S. forces were needed. That concern is overstated. To begin with, the ability to use bases for new missions is always conditional on host government permission. Basing agreements typically stipulate that the United States must consult with host nation governments before conducting any nonroutine operations. A 2016 RAND Corporation study concludes, “The presence of large permanent bases does not increase the likelihood of securing contingency access.” But, more to the point, the United States has historically not had trouble securing basing access in wartime. Indeed, it has been able to add new operating facilities overseas for every major conflict in the past 40 years.
For combat operations that do not rise to the level of a crisis requiring massive mobilization of forces, technological advances in military capability, travel, and communications have made deployment from the continental United States sufficient. This is particularly so with air campaigns. According to the Pennsylvania State University professor Robert Harkavy, “The development of longer range aircraft and ships, plus the development of techniques for aerial refueling of planes and at-sea refueling of ships has had the effect of greatly decreasing the number of basing points required by major powers to maintain global access networks.” Carrier-based airpower can now be used to conduct major campaigns with round-the-clock sorties well beyond coastal reaches in remote areas on short notice and without access to nearby bases.
Even beyond air strikes, U.S. troops can deploy from the United States to virtually any region fast enough. In emergencies, according to RAND, “Lighter ground forces can deploy by air from the United States almost as quickly as they can from within a region.” An armored brigade combat team, for example, can get from Germany to Kuwait in approximately 18 days, only about four days faster than if it deployed from the East Coast of the United States. Admittedly, deploying heavy forces by air in bulk is not plausible for contingencies requiring massive ground troops. But contingencies that truly depend on extremely rapid deployment are rare.
THE RISK OF ENTANGLEMENT
Forward-deployed forces are more vulnerable to attack than forces stationed at home. Thanks to robust deterrence, U.S. overseas bases are not at risk of bombardment in the immediate future, but certain plausible scenarios could make them priority targets. If conflict breaks out over Taiwan or maritime territorial disputes in the East or South China Sea, it could trigger Chinese actions against U.S. assets. A large percentage of U.S. facilities—more than 90 percent of U.S. air facilities in Northeast Asia—are within range of Chinese ballistic missiles. Bases offer only a marginal increase in deterrence at added risk to forward-deployed troops.
Entanglement is another risk exacerbated by the attempt to reassure allies with overseas bases. Much academic literature, including Reputation and International Politics by the University of Washington’s Jonathan Mercer and Calculating Credibility by Dartmouth’s Daryl Press, has questioned the need to take military action solely for the sake of credibility. But the presence of military bases in or near a conflict zone can intensify calls to intervene to satisfy credibility concerns, thus making entanglement more likely.
In the past, the United States stumbled into conflicts because of the entangling influence of credibility, commitments, and the capabilities presented by a forward military presence. By December 1945, U.S. General John R. Hodge recommended full withdrawal of U.S troops from Korea. Secretary of War Robert Patterson argued the same in April 1947. In 1948, the National Security Council proposed withdrawing all U.S. troops by the end of the year. The Joint Chiefs of Staff explained that “Korea is of little strategic value to the United States” and warned that the lingering military presence risked entangling the United States in a war following some provocation on the peninsula. That indeed happened in 1950 when the North invaded the South. Unfortunately, calls to withdraw had gone unheeded.
The presence of forces abroad can also tempt policymakers to get involved in elective wars that they could more easily forgo if the United States lacked in-theater bases. In NATO’s 2011 intervention in Libya’s civil war, for example, the United States bombed Libya from warships in the Mediterranean and from air bases in Spain, Italy, and Germany, among other nearby locations. The weak arguments in favor of U.S. involvement, which included conjectural claims about impending humanitarian disaster and pressure from NATO allies, might have been harder to sell politically if U.S. forces had not already been deployed in the area.
THE FUTURE OF U.S. DEFENSE POLICY
Advocates of a forward-deployed posture contend that it has been a driving force in creating a more peaceful world since the end of World War II by dampening the effects of anarchy and by preventing conflicts from spiraling out of control. This argument is the essence of the logic behind deterrence and reassurance. But other plausible causal explanations exist for the lack of a great-power war since 1945. Although trade and economic interdependence are not always sufficient to stave off conflict between potential belligerents, there is solid evidence that the two factors do reduce the likelihood of war. The destructive power of modern conventional militaries has also made war prohibitively costly in many cases, and the fact that most of the world’s great powers possess nuclear weapons has likely been a major factor in the decline of international conflict. Normative changes in how people see war, from a noble and virtuous ambition to a barbaric last resort, have also contributed to peace among nations.
The U.S. forward-deployed military posture should reflect real U.S. defense interests. The remarkably secure position of the United States, along with the relatively peaceful state of international politics, should allow a withdrawal from this global network of overseas military bases. Rather than defending the security of other states and attempting to stabilize regions of conflict around the world, the United States should encourage allies to carry the burden of their own defense and extricate itself from regional disputes, lest it get drawn into conflicts in which its vital interests are not at stake.