The price of greatness is responsibility. If the people of the United States had continued in a mediocre station, struggling with the wilderness, absorbed in their own affairs, and a factor of no consequence in the movement of the world, they might have remained forgotten and undisturbed beyond their protecting oceans: but one cannot rise to be in many ways the leading community in the civilized world without being involved in its problems, without being convulsed by its agonies and inspired by its causes.

–Winston S. Churchill

When I was an undergraduate in the early noughties, few things could evoke less excitement than an early morning course on the inner workings of the European Union or a lecture on the future of NATO. My eyes glazed over at the very thought of class discussions over European milk quotas or the implementation modalities of the EU Fisheries Law. Similarly, debates over the future of NATO seemed to have a certain uninspiring and circular quality to them. It is perhaps the periods in history that appear the least exciting for young students, however, that end up being those that they subsequently regret the most.

As Robert F. Kennedy wryly noted during an arguably more fraught era, “There is a Chinese curse which says ‘May he live in interesting times.’ Like it or not, we live in interesting times.”

Since the end of the 1990s, Europe had been viewed as a relatively placid, post-historical region, free of illiberalism and territorial tensions. After centuries of warfare, the European continent had finally transcended its age-old rivalries and emerged as a net exporter of norms rather than conflict. The European Union’s technocratic mode of governance placed it at the vanguard of rule-making supra-nationalism, rendering it an inspiring role model for international governance.

Developments over the past few years have upended this vision. In the words of Robert Kagan, the jungle has now entered the postmodern European garden. With Russia’s aggression in Ukraine, geopolitics have made a violent and startling comeback, and ancestral fears of territorial loss have been revived. Only a few years ago, some analysts questioned the very relevance of NATO or exhorted the alliance to expand its vision of collective defense to address transnational threats and contingencies across the globe. If NATO did not exist, wrote one stalwart defender of the alliance in 2010, the United States would not seek to create it. Six years later, this is no longer the case. Excepting the presumptive presidential nominee of the Republican Party, no one seriously questions the utility of the transatlantic alliance. From discussions over the need to combat piracy or human trafficking in remote foreign locales, the focus has squarely returned to “vintage” Cold war issues such as territorial defense and nuclear deterrence.

The early years of the Obama presidency crystallized a clear consensus that U.S. forces were somewhat overinvested in Europe and underinvested in more critical regions, such as Asia. Under the aegis of the pivot or rebalance to Asia, the United States would progressively transfer a larger portion of its military resources and attention from West to East. This was to be accompanied by a large-scale reduction in defense spending and a prolonged effort to “reset relations” with the Kremlin.

With the benefit of hindsight, we now know that strategic practitioners on both sides of the Atlantic were mistaken in their belief that European peace was an end-state rather an interlude and overly optimistic in their hope that Russian revanchism could be tamed through engagement. The 2008 conflict in Georgia should have served as the first clear warning of things to come, but too many viewed it as merely peripheral to European security.

Eight years later, the ramifications of Russia’s post-Georgia military modernization have been made apparent in both Ukraine and Syria, which has become to the Russian armed forces what the Spanish Civil War was for the German Wehrmacht — a giant testing ground for new weapons systems and tactics.

Russia’s revived military prowess and assertiveness has generated fear and anxiety throughout Eastern and Central Europe. This foreboding is particularly palpable in the Baltic States, which are the most vulnerable to aggression and disruption by virtue of their small size, location, and ethnic composition (in the case of Latvia and Estonia). Countries such as Poland are sizably increasing their defense spending, and historically neutral nations such as Sweden and Finland are now openly debating joining NATO. In addition to a heightened focus and debate on conventional deterrence among European frontline states, the continued viability of NATO’s nuclear force posture in the face of Russia’s focus on sub-strategic nuclear warfare is in doubt. Taking all this into account, it seems clear that the Obama administration has underestimated the depths of the challenges currently fracturing the European continent. The task falls to the United States not only to shore up the military balance along the Eastern periphery, but also to inject unity and strategic purpose into a Western alliance system that otherwise risks unraveling at the seams.

A Fractured Continent

Indeed, even as threats loom to the east, Europe faces growing challenges from the south and from the spillover effects of Middle East’s implosion. European democracies have successfully absorbed waves of migration in the past, whether after the Spanish Civil War or during the Boat People crisis in the late 1970s and early 1980s. Yet the sheer scale of the current movement of refugees is unprecedented and has placed a severe strain on traditional EU values of unity and solidarity. Clear fractures have been exposed within the Union over how to handle such large population flows, particularly in a context of economic difficulty. As Nathalie Nougayrede noted, a decade after many Eastern European countries joined the EU, “a political and cultural gap still divides the continent — and its scale may well have been underestimated.”

Meanwhile, fears of mass-casualty terrorist attacks have become pervasive following the slaughters in Paris and Brussels and constant revelations of newly foiled plots all across Europe. Although the U.S.-led campaign against ISIL has been underway for almost two years, the extremist proto-state has yet to collapse. Coalition airstrikes may have succeeded in blunting its territorial expansion and in disrupting the financing and tempo of its operations, but ISIL still rules over 75 percent of the territory it initially controlled. In the absence of a well-coordinated air-ground campaign, it is unlikely that the group will face eradication—or a complete reduction in its ability to draw troubled individuals to the blood-soaked lands of the so-called caliphate—any time soon. In the two years since its emergence, it has trained and radicalized thousands of young men and women from overseas. Its operatives have commandeered large-scale attacks against civilians across the globe, dispatching suicide bombers to the heart of major Western metropolises and shuttering leading hubs of global trade for several days. While European publics wrestle with the fears of homegrown terrorism and the severe challenge posed by the thousands of its citizens radicalized in Syria, a recent Europol report suggests that ISIL has begun a targeted policy of recruitment among Europe-bound refugee populations. This will no doubt have an impact on European public opinion, strengthening the position of those hostile to the acceptance of more refugees.

This climate of fear should be viewed within the context of another troubling phenomenon: the rise of illiberalism within Europe. Over the past few years, extremist and populist movements have been ascendant, surfing on public fears, concerns, and frustrations. While these movements all present certain differences—some originate in the extreme left, some in the extreme right—there are also some abiding similarities, most notably in their rejection of the governance structures of the European Union and in their passionate defense of national autarky and insularity. In addition to their anti-EU and anti-immigration rhetoric, some far-right groups also profess an admiration for socially conservative strongmen in the vein of Vladimir Putin combined with a latent hostility toward the United States. This is something that Moscow is well aware of and seeks to cultivate.

More importantly, the insidious nature of the threat posed by this new brand of European illiberalism extends well beyond minority parties or fringe groups. Indeed, in some cases, the leadership of key European nations, such as Viktor Orban’s government in Hungary or the ruling Law and Justice party in Poland, have taken a violent lurch to the right and displayed neo-authoritarian tendencies. Such developments do not bode well for European unity, which since the end of the Cold War has been embodied by a community of values as well as of interests.

Last but not least, the very real possibility of Brexit could lead to a further unraveling of the European order, reigniting regionalist and secessionist movements in places ranging from Scotland to Catalonia and Corsica.

No Common Vision for Security

The European continent is not only strongly divided on socioeconomic issues, it is also increasingly torn between competing national security priorities. Polling data shows that, for the populations of many Western European countries, Russian irredentism and creeping coercion is of less immediate concern than the fear of being machine-gunned at a concert hall or immolated in a subway car. Meanwhile, the leaders of nations such as Poland, which do not face similar counterterrorism challenges, have expressed frustration over what they perceive as an overemphasis on the challenges emanating from the south, rather than from the east.

It is perhaps inevitable that such divisions should materialize within a union of 28 nations animated by disparate historical experiences, equipped with unequal levels of military resources, and confronted with different geostrategic predicaments. The turmoil engulfing the Old World’s periphery has peeled away at Europe’s residual postmodern illusions, exposing raw divisions and divergent hierarchies of interests. That said, some European nations have endeavored, through their actions and despite their respective resource limitations to transcend this growing intra-European security divide.

As one recent paper from the German Marshall Fund notes:

France is militarily engaged in the Sahel, Iraq, and Syria, but it has also reinforced its air presence in the Baltic area through cooperation with Norway. Italy, despite an acute refugee crisis, has led an eight-month Baltic air policing mission and has offered to lead the Very High Readiness Joint Task Force (VJTF) on a rotational basis. Denmark and Norway have also acted as central players on three different fronts: East, North, and South.

These efforts are to be commended, but it remains to be seen whether they will be economically and militarily sustainable, despite the fact that many European nations have begun to raise their defense spending or reverse budgetary cuts.

The Revival of Territorial Defense

Indeed, the darkening of Europe’s threat environment has led to a wider conceptual shift accompanied by a revival of traditional concepts of territorial defense, particularly in the so-called frontline nations, such as Poland or the Baltic states. All along Europe’s northern and eastern edges, military planners are focusing on deterrence by denial, and in some cases they are recalibrating defense postures and force structures away from coalition-based expeditionary operations toward operational concepts emphasizing national self-defense. The works of unconventional European military theorists from the Cold War, such as Guy de Brossollet or Hans Von Dach, what with their focus on civilian resistance, modular defense, or “techno-guerilla” operations, are being dusted off and rediscovered in a new light. For smaller Nordic and Baltic nations, conscription-based forces have become increasingly attractive, not only as a means of offsetting conventionally superior Russian forces, but also as a means of bolstering social resiliency and better resisting sub-conventional and/or hybrid aggression.

One might argue that this constitutes a net plus for the United States. Indeed, U.S. officials and commentators have long pointed to the unsustainability of the current NATO model, whereby Washington devotes the lion’s share of military and financial resources to Europe’s defense. The fact that leading U.S. presidential candidates have chosen to base their foreign policy platforms on the systematic denigration of U.S.-led alliance structures should not detract from the genuine and justifiable concerns in Washington over the deeply skewed nature of the transatlantic division of labor. In this light, the fact that European countries are finally investing more in their own defense should no doubt be welcomed with open arms.

That being said, a European continent riddled with strategic anxiety and compelled to devote an ever-growing portion of its finite resources to shielding itself from Russia’s predations and the tides of chaos rippling through the Middle East, is not in Washington’s best interests either. For example, consider the case of France, the European country which has arguably contributed the most to global security in the past five years, playing an important military role in Syria, Iraq, Libya, Mali, and across vast tracts of the Sahel. Since the terrorist attacks of 2015, Paris has found itself compelled to deploy in Operation Sentinelle over 10,000 troops for internal security missions. Operation Sentinelle is now the largest ongoing French military operation,] and accounts for over half of all French troops currently deployed. This is another form of “territorial defense” which is arguably even more costly, and even more detrimental to the ability of a leading European military power to conduct extra-regional operations. Indeed, were a major crisis (say in Libya) to erupt tomorrow that demanded the presence of a large multinational ground force, it is uncertain that a severely overstretched French military could provide much in the way of additional capabilities.

As John Deni of the U.S. Army War College notes, a more pronounced focus within NATO on territorial and/or homeland defense does present the risk of certain opportunity costs:

Capabilities most necessary for territorial defense – such as heavy armor or artillery – differ from those necessary for expeditionary crisis management operations—such as strategic air- and sealift, mobile medical support, overseas intelligence networks and capabilities, and deployable logistics capabilities. Certainly, one must be careful not to overemphasize the distinction between forces necessary for territorial defense versus those necessary for expeditionary operations…. However, without specialized expeditionary capabilities such as those noted above, Alliance forces are limited to territorial defense and unable to project enough force to make a difference.

Deni is right to caution against framing this tradeoff in an overly simplistic, binary fashion. After all, leading European military powers such as France, the UK—and to a lesser extent Spain, Italy and Germany—will remain theoretically capable of conducting small-scale expeditionary campaigns, and they continue to invest in such capabilities. The development of the Combined UK and French Joint Expeditionary Force (CJEF), for instance, provides a concrete and encouraging example of this continued commitment. European strategists’ reinvigorated focus on countering anti-access and area denial challenges — both along the EU’s eastern periphery and in the Persian Gulf — is another indication of European militaries’ continued willingness to plan for “over the horizon” contingencies. That being said, the question may not be so much that of willpower as of how to best adjudicate limited resources in an increasingly multi-vectored threat environment. As mentioned earlier, France may soon encounter such a dilemma if it continues to task large numbers of troops with domestic operations. Simply put, it may prove impossible for even Europe’s most advanced militaries to successfully hedge against all forms of threat.

In the past, certain U.S. officials have dismissed European militaries’ ability to bring much in added value to U.S.-led operations overseas, but American soldiers who served alongside their European counterparts in places such as Afghanistan would no doubt beg to differ. Perhaps more importantly, the presence of allied soldiers on the ground has fulfilled an often vital symbolic role by lending greater international and domestic political legitimacy to U.S. led military operations. In the future, would a war-weary American public, increasingly leery of overseas commitments, be willing to support a wholly unilateral U.S. intervention without even the nominal presence of a few European brigades?

Looking beyond the quantifiable military costs of a European continent newly under siege, there are certain broader issues to take into account. A European Union split between north and south, east and west, regions and nation-states—all reeling under the combined threats of sub-conventional attacks and territorial aggression—is not an entity that can act and think confidently on the global stage. As we transition from an era of unipolarity to one of great power competition, Washington will need the support of its likeminded Western partners, not only in shaping normative discourse with regard to issues such as freedom of navigation, but also in preserving a favorable balance of power in key regions such as the Asia-Pacific and the Middle East.

The forthcoming NATO summit in Warsaw provides the United States with the opportunity to show greater determination and dexterity in addressing European security concerns—not only to the east, but also to the wider south, and particularly in places close to European shores, such as Libya. While Washington has made an impressive show of solidarity via the quadrupling of funds devoted to the European Reassurance Initiative, diplomatic efforts will need to be expended in terms of alliance management. This is particularly important following the Obama administration’s decision to publicly air its disdain for European “free-riding”—a bizarre public communications strategy whose downside effects have perhaps yet to be fully appreciated on this side of the Atlantic. As Henry Kissinger has written, the United States has historically viewed the transatlantic alliance as “not so much countries acting congruently to preserve equilibrium, as America as the managing director of a joint enterprise.” The United States must revert to its most effective role: an external actor that adds direction and purpose to an otherwise divided continent and heterogeneous assemblage of democracies. The Old Continent needs the help of the New World in developing a truly joint strategic vision for a deeply troubled era, perhaps now more than ever since the end of the Cold War.

Iskander Rehman is a Postdoctoral Fellow in the Project for International Order and Strategy (IOS), at the Brookings Institution. He can be followed on twitter @IskanderRehman.