Before Deploying More U.S. Forces to Europe, Consider the Consequences

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In 1983, 1.3 million West Germans took to the streets in one of the largest protests the country has ever witnessed. Their goal was to impede the decision to deploy new intermediate-range nuclear forces to West Germany. Similar protests took place in Belgium, Italy, the Netherlands, and the United Kingdom, where the missiles were planned to be installed as well. Ironically, the United States had ordered these deployments specifically to assure its allies. Yet, it hardly seemed to make citizens feel more secure in any of the chosen countries. This historical episode raises questions about the effects of U.S. military deployments and what they mean for national defense policies in host countries.

Answering these questions is of great relevance, not least because the United States has once again announced it will deploy additional military assets on the territory of its European allies in reaction to the ongoing Russian attack on Ukraine. The stated aim is to deter Russia, reassure European NATO allies, and thereby limit the impact of Russian efforts to intimidate its neighbors. Critics of this approach, such as Barry Posen, were quick to bring forward a familiar argument: The additional U.S. military presence in Europe will ultimately put in jeopardy recent European pledges to step up defense contributions, since Europeans may hide behind U.S. protection and fall back into a recognizable pattern of free-riding. This view is correct in that U.S. military deployments may indeed undermine European defense contributions. However, it oversimplifies why this would be the case.



A significant share of citizens in countries that host the U.S. military do not feel protected by the deployment, which undermines common free-riding allegations. To show this, we conducted a survey experiment in Germany with an accompanying analysis using over 25 years of European and World Values Survey data. There is indeed robust evidence that citizens systematically discount their own defense obligations if the United States deploys its military in their country. However, instead of being assured, our survey finds that U.S. deployments can also scare host-state populations. This is because some citizens fear being entrapped in a war caused by the provocative posture of an overly risk-friendly guardian. Thus, while U.S. officials blame allies for alleged free-riding, many people in these countries feel more vulnerable due to the U.S. presence rather than safer. In the end, both those that feel protected and those that feel put at risk react with the same tendency to de-prioritize national defense. This is problematic in the current context because it could undermine the defense spending of allied states in Europe and allow Russia to exploit fears of escalation.

Allied free-riding was pushed into the spotlight in recent years by former U.S. President Donald Trump. Among other actions, he threatened the withdrawal of troops from Germany over alleged NATO payment deficits and demanded that South Korea pay more to the United States for troops based on its soil. Except perhaps for Trump’s unusual bluntness, this was by no means a new development. Indeed, since the beginning of the Cold War, American presidents have pushed allies to step up their defense contributions, often by tying such demands to a continued military presence in their region. However, these announcements were for the most part empty threats. In reality, the United States has time and again increased its military presence in allied regions when tensions started to rise. Unsurprisingly then, President Joseph Biden has pledged to deploy additional military forces to Europe as a reaction to the ongoing Russian attack on Ukraine. The announcement was made at the NATO Madrid summit in June and includes a new permanent military headquarters in Poland, the deployment of F-35 jets to Britain, and troop deployments to Romania. Earlier this year, the Biden administration had already approved the additional deployment of 20,000 troops to Europe for a new total of over 100,000 U.S. troops on the continent.

According to the United States, the aim is to bolster deterrence in Europe and successfully defend its partners in the region if push comes to shove. There are two audiences for these deployments: first, potential adversaries, and second, allies that demand tangible assets to underpin U.S. security guarantees. But assuring allies can also come at a cost if it undermines their own willingness to invest in national defense. Scholars have typically looked at defense burden-sharing by comparing allies’ percentage of GDP spent on national defense to see if they punch above or below their weight. These studies offer mixed findings across space and time. While such research is doubtlessly important, we argue that taking a closer look at public opinion in allied states can lead to a fuller picture of the underlying dynamics in a society. In fact, U.S. forward deployments go hand in hand with diverging, and often negative, perceptions among host-state populations. By contrast, if allies wanted to piggyback on U.S. security guarantees (and free-ride), such deployments should be widely popular and instill a sense of protection (assurance). Such nuance can only be uncovered by examining public opinion.

There exists surprisingly little research on the relationship between military deployments and the subjective need for national defense by host-state citizens. Some notable exceptions are Lauren Sukin’s finding that credible U.S. commitments increase South Korean public approval of a national nuclear weapons program and Jo and Tor Jakobsen’s study on the connection between U.S. troops and a lower willingness to fight among the host population. The lack of research exists even though most close U.S. allies are, and have been, democracies. Thus, what citizens think is important, and it can influence the broader national defense orientation. It is true that democratic governments can push through some unpopular policies. For example, there is considerable evidence that in four out of the five remaining NATO nuclear host states (Belgium, Germany, Italy, the Netherlands, and Turkey), the public has long held unfavorable views toward these arrangements — yet they continue to exist. However, in other instances, public opinion has evidently limited government conduct. Germany only brought itself to purchase the F-35 as a nuclear-capable replacement of its aging Tornado fleet after the Russian attack on Ukraine. For years, consecutive governments had postponed the decision, passing the burden to future ruling coalitions. This hesitancy also applies to the fulfillment of NATO’s 2 percent defense spending goal, which German governments had arguably avoided to implement until Russia’s attack in February because it would have not gone down well with voters.

To study the relationship between military deployments and public sentiment, we first analyzed public opinion data spanning four decades from the European and World Values Surveys to shed light on how conventional and nuclear military deployments affect NATO citizens’ opinions on national defense. Our preliminary results consistently show that hosting U.S. troops or nuclear weapons is related to host-state citizens (1) showing a lower willingness to fight for their own country in the event of war, and (2) reducing the importance they place on having strong national defense forces.

Too often, research has stopped at this point with concluding claims of free-riding. However, we wanted to dig deeper into what drives these results. Especially in Western Europe, we believe there to be widespread skepticism toward the United States alongside popular pacifist sentiments. Host-state citizens may actually feel more insecure because of these deployments, rendering insinuations of free-riding on U.S. security guarantees nonsensical. This is because U.S. military deployments are viewed by some as self-serving tools that will either provoke unnecessary conflict with an adversary, fuel an escalation spiral, or even worse, entrap their state in a war it otherwise would not have to fight. As a result, these citizens will also not support ambitious defense efforts, such as investments in the national military, which they see as being corrupted by the United States. Essentially, they do not want to contribute to what they see as a provocative, foreign-imposed agenda. This idea is certainly not new. Indeed, the late Michael Howard voiced a similar thought in the 1980s. However, despite its relevance, there have been few empirical tests of whether U.S. military deployments can actually assure allied citizens.

To fill this gap, we fielded a survey experiment in Germany in June with a representative sample of 2,200 respondents. We provided a factually correct description of Germany’s NATO member status as well as the number of U.S. troops and nuclear weapons deployed in Germany. We then asked about the motives behind these deployments. We found that one-third of respondents believe such deployments exist solely to further U.S. national security or U.S. political or economic interests, rather than to protect Germany or other allies. Indeed, only about 20 percent of respondents thought that the United States deployed their military solely to protect Germany and its allies.

We then conducted an experiment by randomly dividing the respondents into four groups. In addition to a control group, we assigned participants in the other three groups to one of three scenarios: (1) the withdrawal of 18,000 U.S. troops, (2) the withdrawal of all U.S. nuclear forces, or (3) both withdrawals. Our results are quite remarkable. The treatments (U.S. military withdrawals) heightened national defense contributions based on a broad range of measurements: from the expressed willingness of Germans to fight for their own country, to how important they rate the German army, to increased defense spending. In turn, this also means that the presence of the U.S. military is associated with lower levels of all these measures, which is bad news for the United States if it keeps a large global footprint. On the upside from an American point of view, we also find that U.S. military deployments seem to lower the desire to develop a German nuclear bomb. Perhaps most importantly, contrary to the free-riding hypothesis, we found little evidence that military withdrawals would actually make citizens feel less secure. Compared to the control group’s scenario in which no withdrawals take place, we did not find that military withdrawals are associated with a discernibly higher (perceived) likelihood of war involving Germany or other European allies, whether conventional or nuclear. If anything, our results suggest that citizens would view such events as less likely following a U.S. military withdrawal. Notably, these sentiments seem to persist despite the ongoing Russian attack on Ukraine.

While these are only preliminary findings, they strongly indicate the complicated nature of U.S. military deployments, which do not necessarily seem to make host-state citizens feel protected. On the contrary, they can lead to a lower willingness among the population to contribute to national defense. What are the implications for decision-makers, both in the United States and in allied countries? For one, U.S. officials should put more thought into how signals of assurance are actually being perceived. While military deployments may be well intended, host-state populations do not always see them this way, as our survey findings suggest. If a deployment increases citizens’ threat perceptions, then Russia can exploit this to its advantage by exacerbating existing threat environments through thinly veiled warnings of nuclear escalation. However, this does not mean that the United States should pursue isolationism by withdrawing its forces from around the world. Rather, decision-makers must acknowledge and carefully weigh the complex and multi-layered effects that a U.S. military presence brings about in host states. Especially for deployments that are first and foremost designed to assure allies, it is important to more thoroughly question if the action is suitable to achieve the desired outcome, and at what price.



Alexander Sorg is a Ph.D. researcher at the Hertie School’s Centre for International Security, where he was awarded a scholarship through a project funded by the Stanton Foundation. His research interests include nuclear weapons, assurance, and alliances. In his doctoral thesis, he is focusing on the causes and consequences of U.S. foreign-deployed nuclear weapons.

Julian Wucherpfennig is professor of international affairs and security at the Hertie School, Berlin. His research focuses on the strategic logic of armed conflict, including civil war, terrorism, and nuclear security, and has been published in the American Political Science Review, American Journal of Political Science, Journal of Politics, International Organization, and World Politics, among others. His new book, Sharing Power, Securing Peace?, co-authored with Lars-Erik Cederman and Simon Hug, was just published by Cambridge University Press.


Image: U.S. Army photo by Pfc. Destinee Rodriguez