The Future of the Transatlantic Alliance: The End of the American Century or the Beginning of a European One?
By Matthew Parish
Monday 9 November 2026
For almost eighty years, the transatlantic alliance has been one of the great organising principles of international politics. It has provided Western Europe with security, the United States with a network of reliable allies and the international community with a degree of stability that would have seemed inconceivable amid the ruins of the Second World War. The alliance has survived the Cold War, the collapse of the Soviet Union, disagreements over Vietnam and Iraq, the expansion of NATO into Eastern Europe and repeated predictions of its imminent demise. Yet the political upheavals of the present decade have exposed a fundamental question that can no longer be avoided: can a strategic alliance survive when its members increasingly disagree about what they are defending, whom they are defending against and what sacrifices they are prepared to make?
The transatlantic relationship was never simply a military arrangement. It was a grand political settlement founded upon a particular understanding of modern civilisation. The United States, having intervened decisively in two European wars, concluded that its own security was inseparable from the stability of the European continent. Western European governments, exhausted by two catastrophic conflicts and confronted by the expanding power of the Soviet Union, accepted that their security could no longer be guaranteed by their own military establishments. The result was an unprecedented arrangement in which an enormously powerful country voluntarily undertook to defend a collection of smaller countries across an ocean, while those countries accepted American political and military leadership in exchange for protection.
The North Atlantic Treaty of 1949 formalised this arrangement, but its intellectual foundations were considerably broader. The Marshall Plan helped reconstruct Western European economies, American nuclear weapons deterred Soviet expansion and the institutions of European integration gradually transformed a continent previously characterised by recurrent warfare into an increasingly prosperous community of democratic states. The remarkable achievement of this system was that Europeans eventually came to regard international peace not as an exceptional achievement but as the normal condition of political life. For generations born after 1945, the possibility of a major European war became something encountered principally in history books.
The Russian invasion of Ukraine in February 2022 shattered that complacency. Suddenly Europe was confronted with a conventional war involving hundreds of thousands of soldiers, enormous quantities of artillery ammunition, the systematic destruction of civilian infrastructure and territorial ambitions that recalled the darkest episodes of the twentieth century. The war also revealed that the transatlantic alliance had become dangerously unbalanced. The United States still supplied many of the critical military capabilities upon which European security depended, while European governments had spent decades reducing their armed forces and diverting public expenditure towards domestic priorities. The peace dividend following the Cold War had been enjoyed with enthusiasm, but its underlying assumptions had never been adequately examined.
The return of Donald Trump to the American presidency in January 2025 has accelerated a fundamental reassessment of this arrangement. Trump is frequently portrayed in Europe as an aberration, a temporary departure from an otherwise stable tradition of American internationalism. This interpretation is comforting but probably mistaken. His political success reflects deeper changes within American society, including declining confidence in international institutions, dissatisfaction with the economic consequences of globalisation and growing resentment towards allies perceived as enjoying American protection without contributing proportionately to its costs. Trump has articulated these sentiments with unusual bluntness, but he did not invent them and there is little reason to suppose that they will disappear when he eventually leaves the White House.
The significance of this shift has become unmistakable in American strategic doctrine. Washington's 2026 National Defense Strategy explicitly identifies China and the defence of the American homeland as higher priorities than European security, while characterising Russia as a persistent but manageable threat. European states are expected to assume primary responsibility for their conventional defence, with the United States providing more limited support. This is not necessarily a declaration of American isolationism. Rather, it represents an attempt to redefine the alliance as a partnership between states that must increasingly provide for their own security instead of relying upon an American security guarantee whose political foundations have become uncertain.
There is a legitimate strategic argument behind this American position. The European members of NATO collectively possess vastly greater economic resources than Russia, notwithstanding the Kremlin's willingness to devote a disproportionate share of its national income to military expenditure. There is no obvious reason why wealthy European societies should remain permanently dependent upon American taxpayers for their conventional military protection. Moreover, the United States faces an increasingly formidable strategic competitor in China, whose economic scale, technological capabilities and naval ambitions create challenges fundamentally different from those presented by Russia. American policymakers reasonably ask why the defence of Europe should remain their country's overriding overseas military commitment when the centre of global economic and strategic competition has shifted towards the Indo-Pacific.
Yet the difficulty lies in distinguishing a legitimate demand for European responsibility from a potentially disastrous abandonment of the institutions that have made European peace possible. NATO is not simply an agreement about expenditure. It is an extraordinarily elaborate system of military planning, intelligence cooperation, communications, command structures, logistics and political consultation. American military power is embedded within the alliance in ways that cannot easily be replaced by increasing European defence budgets. Strategic reconnaissance, satellite intelligence, integrated air defence, aerial refuelling, military transport and nuclear deterrence all depend, to varying degrees, upon capabilities that the United States has developed over decades. An abrupt American withdrawal would therefore create vulnerabilities that even substantial European expenditure could not immediately remedy.
European governments have begun to appreciate the scale of this problem. At the Hague NATO summit in 2025, member states agreed upon a target of expenditure amounting to five per cent of gross domestic product by 2035, comprising 3.5 per cent for core defence requirements and up to 1.5 per cent for broader defence and security-related investments. The Ankara summit in July 2026 subsequently reaffirmed the alliance's commitment to collective defence. Meanwhile the European Union has launched an ambitious defence readiness programme intended to strengthen military production, improve procurement and overcome critical weaknesses by 2030. These developments suggest that the transatlantic alliance is not collapsing so much as undergoing an exceptionally uncomfortable redistribution of responsibilities.
The problem, however, is that spending money and developing military power are not the same thing. Europe already possesses an impressive collection of sophisticated weapons systems, military research institutions and defence manufacturers, but its military establishments remain divided between national bureaucracies, procurement practices and strategic priorities. France maintains an independent nuclear deterrent and substantial expeditionary capabilities. Germany possesses formidable industrial resources but has struggled with military readiness. Poland has undertaken extensive conventional rearmament, while the Baltic states have developed an acute understanding of Russian military intentions. These national strengths do not automatically combine into an effective European army, and political disagreements can obstruct the practical military cooperation necessary to exploit them.
Indeed, the most important weakness in European defence may ultimately be political rather than technological. European societies disagree about the nature of the Russian threat, the appropriate relationship with China and the extent to which military expenditure should displace social programmes. Countries on NATO's eastern flank tend to regard Russia as an immediate existential danger, whereas some societies further west perceive the conflict in Ukraine as a distant tragedy with comparatively limited consequences for their own security. These disagreements are amplified by the growth of nationalist and populist movements whose political programmes often combine suspicion of European institutions with a desire to reduce international commitments. A continent that cannot agree upon the meaning of its common security will struggle to organise its defence, however sophisticated its weapons become.
The relationship between political populism and the transatlantic alliance deserves particular attention. In the United States, the MAGA movement has challenged the traditional Republican commitment to American leadership of the Western alliance. In France, political forces associated with Marine Le Pen have questioned important elements of the European integration project. In Germany, the rise of the Alternative for Germany has demonstrated the strength of dissatisfaction with the established political consensus, while comparable movements have gained influence elsewhere in Europe. These movements are not identical, and their attitudes towards Russia, NATO and national sovereignty differ considerably.
Nevertheless, they share a tendency to place immediate national interests above the institutional compromises upon which the post-war transatlantic settlement was constructed.
There is an irony here. The transatlantic alliance was created to protect liberal democratic societies against authoritarian expansion, yet some of the political movements challenging its cohesion have emerged from within those very societies. Liberal democracy permits electorates to reject the strategic assumptions of their predecessors, even when those assumptions have contributed substantially to their prosperity and security. An alliance founded upon democratic values must therefore accommodate the possibility that democratic electorates will periodically choose governments hostile to elements of the alliance itself. This is not necessarily a fatal contradiction, but it means that transatlantic cooperation can no longer depend exclusively upon a relatively narrow consensus among political elites.
Britain occupies a particularly curious position in this changing landscape. Historically she has served as the principal intermediary between continental Europe and the United States, maintaining an unusually close intelligence and military relationship with Washington while exercising considerable influence over European affairs. Brexit damaged this position by removing Britain from the political institutions through which much of Europe's collective economic and strategic policy is formulated. Whatever the original intentions of its supporters, departure from the European Union has not transformed Britain into an independent global superpower. Instead it has complicated its relations with its largest neighbouring economic bloc at precisely the moment when European cooperation has become increasingly important.
There is a powerful argument that history will eventually draw Britain back towards European integration. The geographical, economic and strategic realities underlying British membership of the European Union have not disappeared merely because a referendum produced a different political outcome. Indeed, the growing uncertainty surrounding American commitments makes British cooperation with continental Europe more important than at any time since the Cold War. The security and defence partnership established between Britain and the European Union in May 2025 represented an acknowledgement of these realities, although it fell considerably short of institutional reintegration. A return to full EU membership remains politically uncertain and would require a substantial change in British public opinion, but closer economic and strategic cooperation appears increasingly difficult to avoid.
The future of the transatlantic alliance cannot, however, be understood without examining the position of Ukraine. For Ukrainians, these debates are not abstractions discussed at comfortable conferences in Brussels, Munich or Washington. They concern the daily survival of a sovereign country subjected to Russian aggression. Ukraine has become the principal testing ground for the proposition that European states possess both the political will and the practical capabilities necessary to defend the international order upon which their security depends. If Europe proves unable to sustain Ukraine's resistance without constant uncertainty over American assistance, then its claims to strategic autonomy will remain fundamentally unconvincing.
There is a further paradox in Ukraine's position. Although Ukraine is not a member of NATO, its armed forces have accumulated operational experience of modern high-intensity warfare that few NATO militaries can match. Ukrainian soldiers and engineers have developed remarkable expertise in drone operations, electronic warfare, battlefield adaptation and the integration of relatively inexpensive technologies into sophisticated military systems. European governments increasingly recognise that Ukrainian military innovation can contribute directly to their own security. The country once regarded as a prospective recipient of Western protection is becoming an indispensable source of European military knowledge. This transformation may prove to be one of the most consequential strategic developments arising from the war.
For the alliance's future, the eventual outcome of the Russia-Ukraine war will be decisive. A settlement that leaves Ukraine permanently vulnerable to renewed Russian aggression would undermine confidence in Western security assurances and encourage the Kremlin to test the limits of European political resolve. Conversely, an outcome that preserves Ukrainian sovereignty, establishes credible deterrence and integrates Ukrainian military capabilities into a broader European security architecture could provide the foundations for a substantially more resilient continental defence system. Peace, in other words, cannot be measured solely by the cessation of military operations. It must also be assessed by whether the resulting political arrangements reduce the likelihood of further aggression.
There is nevertheless a danger that Europeans will interpret the present crisis as requiring complete strategic separation from the United States. Such an approach would be economically expensive, militarily hazardous and politically unnecessary. The United States continues to derive enormous benefits from its European alliances, including access to military bases, intelligence cooperation, diplomatic influence, economic relationships and the ability to project power across strategically important regions. Europe remains a major trading and investment partner whose technological and industrial capabilities contribute significantly to American prosperity. A complete transatlantic rupture would diminish American power as well as European security, even if its immediate military consequences would be more severe for Europe.
The better alternative is to reconstruct the alliance upon a more balanced foundation. Europe should assume primary responsibility for its conventional defence, develop a sufficiently integrated military industrial system and acquire the operational capabilities necessary to respond to regional emergencies without automatically requiring American intervention. The United States should remain an essential strategic partner, providing nuclear deterrence, intelligence cooperation and assistance in circumstances where the security interests of both continents coincide. This would represent a transition from European dependence upon American protection towards a more mature partnership between strategically capable allies.
Achieving this transformation will require confronting difficult questions that European politicians have preferred to avoid. Should the European Union develop more extensive common borrowing to finance military procurement? Can France and Britain extend their nuclear deterrents to provide a more credible European security umbrella if American commitments weaken? Should European defence industries consolidate across national boundaries, notwithstanding the political sensitivities associated with employment and technological sovereignty? Can NATO accommodate a more autonomous European military command without creating competing bureaucracies? These are not merely technical questions. They concern the willingness of European states to surrender elements of national discretion in exchange for greater collective security.
The financial implications are equally profound. European welfare states developed during an era in which defence expenditure could gradually decline relative to national wealth, permitting governments to allocate increasing resources towards pensions, healthcare, education and social services. Reversing this process will require difficult political choices, particularly in ageing societies with stagnant productivity and substantial public debts. Military expenditure can stimulate technological innovation and industrial investment, but it cannot abolish the underlying scarcity of public resources. Political leaders who promise both comprehensive rearmament and the indefinite preservation of existing spending commitments without additional taxation or economic reform may discover that arithmetic is less accommodating than electoral rhetoric.
The question of China introduces another complication. European governments have extensive economic relationships with Beijing, while the United States increasingly regards Chinese technological and military power as its principal long-term strategic challenge. A serious confrontation over Taiwan could place European countries in an extremely uncomfortable position, particularly if Washington expected substantial European economic or military support while continuing to reduce its own commitments to European security. The transatlantic alliance will remain viable only if both sides recognise that their geographical priorities differ without concluding that their strategic interests are entirely separate. European security cannot be wholly divorced from developments in East Asia, just as American security cannot be wholly insulated from Russian expansion in Europe.
There is also the question of what remains of the common ideological foundations of the alliance. During the Cold War, the contrast between Western liberal democracy and Soviet communism supplied a relatively coherent political identity. Today's Western societies are far more internally divided over immigration, national identity, economic inequality, environmental regulation and the proper boundaries of state authority. American political discourse has become increasingly polarised, while European politics is undergoing its own realignments. These developments make it difficult to sustain the claim that the Atlantic community possesses a single coherent political philosophy. Nevertheless, a common civilisation need not require complete ideological agreement. It may be sufficient that its members continue to recognise the importance of constitutional government, political pluralism, individual liberty and the peaceful settlement of international disputes.
The essential distinction is between shared interests and shared values. Alliances founded exclusively upon common values may become vulnerable when domestic political cultures diverge. Alliances founded exclusively upon immediate strategic interests may dissolve when the balance of power changes. The transatlantic relationship historically succeeded because it combined both elements, creating institutions capable of managing disagreements without destroying the underlying partnership. Its future will depend upon recovering that capacity for compromise while accepting that the relative distribution of power within the alliance is changing.
Three broad futures are conceivable. In the first, the alliance gradually evolves into a more balanced arrangement, with Europe assuming greater military responsibilities while the United States remains strategically engaged. In the second, political disagreements and competing priorities produce a progressive weakening of American commitments, leaving Europe obliged to construct a substantially independent security system under considerable pressure. In the third, a major international crisis provokes an abrupt rupture, potentially destroying institutional relationships that would take decades to rebuild. Recent analysis of European defence suggests that all three possibilities warrant serious consideration, although the extraordinary depth of existing institutional and military cooperation makes gradual transformation more plausible than immediate disintegration.
The first outcome is clearly preferable, but it should not be confused with an effortless continuation of the past. Europe must demonstrate that it is capable of strategic maturity, while America must recognise that alliances are not commercial contracts in which every obligation can be reduced to a financial calculation. The strategic advantages accumulated through decades of cooperation cannot simply be reconstructed after their abandonment. Trust is an intangible military resource, and once destroyed it cannot readily be restored by presidential declarations or increases in defence expenditure.
For those of us observing these developments from Ukraine, there is something peculiarly disconcerting about the leisurely pace at which some Western governments continue to address questions of military readiness. Ukrainian cities experience the consequences of Russian aggression directly, while European capitals debate procurement schedules extending well into the next decade. The contrast illustrates the difference between treating security as a theoretical public policy problem and understanding it as an immediate condition of national existence. Ukraine's experience should provide an urgent lesson to countries accustomed to assuming that their sovereignty is protected by institutions whose effectiveness they have rarely needed to test.
Ultimately the transatlantic alliance is unlikely to disappear, but the historical era in which its functioning depended upon unquestioned American leadership is drawing towards a close. The United States will remain an extraordinarily powerful country, but it will no longer be willing to bear the principal costs of European defence indefinitely. Europe will increasingly have to provide for its own security, whether through NATO, the European Union or more flexible arrangements among willing states. This transformation may be painful, expensive and politically contentious, but it is not necessarily a tragedy. It could ultimately produce a stronger Atlantic community, founded upon reciprocal commitments rather than institutionalised dependency.
The greatest achievement of the post-war transatlantic alliance was not that it permitted Europeans to remain militarily weak. It was that it created the political conditions under which European states could cease regarding one another as natural enemies. That achievement remains of immense historical significance, and it would be a profound mistake to discard it amid the turbulence of contemporary politics. The task now is to preserve the institutions of cooperation while adapting them to a world in which European security can no longer be guaranteed by American benevolence alone.
The American century may indeed be coming to an end, at least in the sense of unquestioned American predominance over the political and military affairs of Europe. But it does not follow that the Atlantic community must collapse with it. A more independent Europe, capable of defending itself while maintaining a mature strategic partnership with the United States, would represent not the failure of the transatlantic alliance but perhaps its ultimate success. After eighty years of American protection, Europe may finally have to become the strategic adult that the alliance was originally intended to help it grow into.
And from the perspective of Ukraine, where the price of European insecurity is paid every day in destroyed homes and human lives, that moment of adulthood cannot come soon enough.
