After ‘Amexit’

How does Britain build prosperity and peace in a world without American hegemony? Actually it's possible.

The international order is changing - not by design, but by retreat. The slow, uneven withdrawal of the United States from the multilateral system it created between 1944 and 1961 has left allies anxious, institutions vulnerable, and the world now asking questions about what comes next.

This is not a sudden collapse of American primacy, but a kind of strategic “Amexit” which requires us to plan much faster for the shift to a modern concert of power that is probably the best guarantor of peace in the multi-polar world that is coming. And if this ‘Pax Multiplex’ is to be rich in opportunity for the UK then we will need to move quickly to get defence, industrial policy, trade, development and soft power - right.

The new National Security Strategy, Strategic Defence Review, Industrial Strategy, Trade Strategy and Comprehensive Spending Review - are going to be, taken together, a seminal moment for Britain - and Labour.

MAGA?

The greatest irony of President Trump’s mission to ‘make America great again’ is that he is accelerating the end of American hegemony.

In his first term and the first 100 days of his second turn in office, the President has withdrawn the United States from the Paris Climate Agreement, the Trans-Pacific Partnership, UNESCO, the World Health Organization, the INF Treaty, the Iran Nuclear Deal, the Open Skies Treaty, undermined the World Trade Organization by blocking appointments to the WTO’s Appellate Body, slashed funding for the UN, weakened NATO and imposed tariffs which the IMF revealed this week, have helped wipe out £420 billion from global economic growth this year.

Still underway are the 180 day reviews of whether the US should continue to remain in the World Bank and IMF. And a quick survey of the Heritage Foundation’s Project 2025 reveals a huge list of multilateral commitments which President Trump may go onto review.

Project 2025: Proposals for US Treaty Review

This is not only a moment of disruption. I suspect it is an irrevocable transition to a new world - and like all such moments, it creates a tonne of new risk. Why?

Because hegemons are important.

So what do hegemons do anyway?

Hegemons are states like ancient Athens, Rome, the British Empire or the modern United States that so powerful they shape the very order of the world and enforce a stability by supplying economic, military, ideological, diplomatic, and institutional leadership, maintaining peace, spreading values, and fostering global cooperation. Indeed, they are so powerful that some - like Charles Kindleberger - argue that peace and prosperity - are impossible without them.

In the 1970’s, Kindleberger famously argued that international economic order depends on a dominant power willing to act as stabiliser; “for the world economy to be stabilised, there has to be a stabiliser – one stabiliser” to provide the five public goods on which the global economy depends; open markets, counter-cyclical lending, currency stability, macro policy coordination and a lender of last resort.

Britain of the 19th century supplied much of this; free trade, elimination of tariffs and the gold standard to settle international trade. But no-one supplied these goods in the 1930’s with disastrous results, as Kindleberger put it,

‘the United Kingdom was willing but not able, while the United States was able but not willing.’

But beyond the economics, hegemons crucially, supply peace. They are the stabiliser of last resort, the security guarantor, the war-preventer. Athens famously supplied its massive navy to help the Delian League of Greek city-states stay safe. Rome’s legions and fleets kept order enabling citizens throughout a vast territory to live without fear of foreign invasion. After defeating Napoleonic France, Britain became the “global policeman” powerful enough to ensure freedom of navigation on the world’s seas, patrolling sea lanes, suppressing slavery (after 1807) and interdicting pirates.

But there is more. Hegemons are the fountain heads of the soft power that shape the ideological contours of international order. As Thucydides noted, “hegemons are by definition powerful states, but successful hegemonia is based on more than material capabilities.” Athens was an arsenal of hard power. But as Pericles explained it was also the model of democracy, home to the school of Hellas, an exemplar in the arts, philosophy, and civic freedom that stood opposed to Persian “barbarism.” It was admired. It held the moral high ground. Rome in its day, was the foundation-head of civilization, law, and language famed for its justice, and eventually, Christianity. Equally, Britain at its height was the standard-bearer for liberal values, the rule of law, and (at home at least) parliamentary democracy, free trade and classical economics; a teacher of nations.

Equally, hegemons are the spiders at the centre of web of alliances, partnerships, and client relationships through which they orchestrate collective action. They convene the summits, mediate the disputes, defuse the crises, persuade, cajole, and hold the pen when treaties are signed. Athens was the centre of the Delian League. Sparta, the Peloponnesian League. Imperial Britain was the offshore balance of power in Europe and London the hub of international diplomacy.

Finally, hegemons supply institutional leadership; a rules-based international system which channel power through institutions that outlive the dominance of any single state.

America: the post-war hegemon

Post-war America learnt these lessons. Post-war America met these tests. With unmatched military strength and a (brief) nuclear monopoly, post-war America effectively guaranteed the security of dozens of nations, from Western Europe to East Asia, its troops stationed from Germany to Japan.

America was the post-war architect of the free trade and economic stability. In 1944, it led the creation of a new dollar-centred monetary order managed by the IMF and World Bank. The U.S. led the creation of the General Agreement on Tariffs and Trade (GATT) to liberalise trade. Its Marshall Plan helped rebuild destroyed markets, while the OEEC it helped found (which became the OECD in 1961) coordinated the drive for growth.

America ruthlessly put ideology front and centre in its hegemonic role, extolling the virtues of freedom, democracy, and human rights. It was the leader of the “Free World” in opposition to Soviet totalitarianism. Its soft power was/is the cornerstone of U.S. dominance: from Hollywood films to the very idea of the “American Dream.”

Post-war America was the greatest alliance builder in history, its proudest achievement to spearhead the creation of the United Nations in 1945, alongside the creation of NATO, bilateral treaties across Asia Pacific, the Nuclear Non-Proliferation Treaty (NPT), trade agreements from GATT to the WTO. It was the mediator-in-chief of the world’s toughest conflicts. It was instrumental in formulating the Universal Declaration of Human Rights (1948) and promoted the Geneva Conventions. It took the initiatives on climate change diplomacy from the Kyoto Protocol to the Paris Agreement.

What is more, the US led the institutions it helped create, setting the agenda as the first among equals on the UN Security Council and quarterback of the IMF, World Bank, and the WTO. In international affairs it was the author of the ‘Washington Consensus’ that underpinned everything from financial stability, to development loans to trade rules.

No more.

After Amexit

The end of America hegemony has been coming for along time. It was not so long after Francis Fukuyama began preaching the ‘End of History’ (1989) and the triumph of the liberal order that China’s Premier Wen was talking about the dawn of something very different: the multi-polar world.

In practice, for all the disruption, American power remains immense - and will remain immense for years to come. But what replaces U.S. hegemony is uncertain. Some fear a return to anarchy. Others see the rise of authoritarian power blocs.

For writers like Robert Kagan, the moment is full of peril. Kagan has long warned of the risks of American retreat, arguing that America bears a “special obligation” rooted in its founding creed and unique power to champion universal values like democracy and human rights, and that moreover, today’s liberal world order still

“requires a single, order-inducing hegemon to enforce the rules.”

It is, argues Kagan, America’s willingness to “police the globe” that was the midwife of the unprecedented era of general peace and prosperity since 1945. And if American power wanes, Kagan warns us, aggressive regimes will fill the void and conflict spread, shrinking the prize of liberalism.

I suspect Henry Kissenger would agree. While Kissenger wrote so eloquently about the virtues of a balance-of-power logic, he nevertheless observed in World Order, that “the international order is not self-generating. It requires constant engagement and leadership.” He was a firm believer in the pre-requisite of American leadership for “No truly global order can ever arise until it is accepted by a dominant power prepared to sustain it.”

Yet this priority is not President Trump’s priority. And so the question President Trump now poses for us is acute: how to manage global order after hegemony, not through dominance of some, but through cooperation among a set of states still committed to the basic principles of international stability.

In the long run, perhaps our best hope is to effect a shift towards the balance of power that preserved the peace through the long 19th century when Britain, Austria, Prussia, France, and Russia maintained a rough equilibrium and whenever one state became too powerful, others formed alliances to restore balance. Thus, might was evenly distributed and states counterbalanced each other to prevent any one state from becoming too strong.

But we are not there yet.

Today’s multi-polar world is, at best, staggering towards ‘balance-of-power politics’ as China asserts its influence (Belt and Road, regional institutions, aggression in the Taiwan Strait), Russia acts as a revanchist, violent disruptor, and middle power powers like the EU, India, Japan all seek more autonomy, regional hedging, new alliance structures and a competition for spheres of influence.

Today, there is no no stable concert system strong enough to deter violence, as we see all too well in the Ukraine, Gaza and across sub-Saharan Africa, and crucially, there is a risk that our institutions - the hegemony’s bequest - persist but grow weaker. The result? Strategic uncertainty, not equilibrium; a fluid, unstable multipolar world, with some elements of balance-of-power politics emerging but without the structure or predictability of systems past.

Hence the importance of the insights in Ngaire Woods’ brilliant piece for Foreign Affairs published this month.

Woods draws on the insights of the great theorist Robert Keohane, who in his classic book After Hegemony, noted that while the world tends to require a hegemon to create a multi-lateral system we do not necessarily need a hegemon to run it - as long as there are coalitions of the willing prepared to stand up and play their role; hegemons build international institutions so that cooperation can endure even after its dominance recedes. They might be needed to kick-start cooperation, but thereafter strong institutions and norms can ensure that economic openness persists “even after the decline of the hegemon” – lifting the absolute dependence on one nation’s will.

Cooperation is therefore still possible as long as states share interests, repeat interactions, and institutionalise rules. Keohane’s insight was that once these institutions and regimes are in place, they reduce transaction costs and bind states together, so that even if the hegemon’s relative power declines, cooperative habits and rules can persist.

As Woods reminds us, the key is to look beyond the ‘supply side’ of power and focus on the ‘demand side’ for order. Order is not purely sought or supplied by the hegemon - it is also demanded by states with an interest in stability. European integration, the BRICS+ initiatives, OPEC+, regional reserve mechanisms such as the Chiang Mai Initiative or the African Financial Stability Mechanism all illustrate what Woods calls demand-driven multilateralism. These frameworks may lack a hegemon—but they do not lack purpose, legitimacy, or resilience.

Robert Keohane would agree. Indeed, Keohane observed that countries demand cooperative regimes because they solve collective problems. In other words, a farsighted hegemon will build the house of world order so well that it can stand even when the hegemon is no longer holding up the roof alone. (That is our debt to America).

This line of thought has its echoes in the work of scholars like Ian Clark, John Ikenberry, and Alexander Cooley who in their own ways have all emphasized that hegemony today may not rest on a single dominant actor but a ‘collective hegemony,’ a group of major powers share responsibility for maintaining global order through institutions, alliances, and good leadership. Perhaps over time, this may prove to become a modern concert of powers: a system in which the world’s major economies and regional anchors—absent a single hegemon—coordinate interests, contain rivalries, and steward key institutions.

And if we are lucky this shift in the world order and the wane of American leadership may prove a blessing, because hegemons are always a curse of sorts, rarely resisting resisting the temptation to use their power for their own gain and too often (Britain, Rome, Athens, but also America in Iraq) colonial domination of lesser powers. Kissinger once observed that the Congress of Vienna worked not because power was balanced, but because it was restrained. It survived because states agreed to rules they could enforce, but rarely resorted to in practice.

But this is amongst history’s exceptions. Too often, the very hand that steadies the great powers strike the weak, waging war against smaller nations even as it claims to guard the world’s order. It was ever thus. Hence Thucydides’ lament at how Athens at first earned hegemonic legitimacy by leading the Delian League against Persia. But as the years wore on, lost its concern for justice and the common good corroding its authority, turning allies into resentful subjects, and ultimately issuing its infamous warning to the Melians, that ‘strong do what they can and the weak suffer what they must’.

So, what of Britain?

In this emerging order, the United Kingdom has a crucial role to play.

We are no longer, thankfully, the imperial power we were. But we are a globally connected, diplomatically agile, nuclear-armed actor with influence in both the Euro-Atlantic and Indo-Pacific spheres. We are perfectly place to function as what Keohane might call a “system-supporting power”—a state that helps bridge institutions, sustain cooperation, and anchor a more pluralist stability.

This moment of transition is a world of risk - and opportunity for Britain.

It is risky because we are going to rely on American leadership for critical aspects of our security for many years to come. But, there is opportunity because in this emerging world, the UK can no longer act as a junior partner to American strategy. We must now operate as what Keohane called a “system-supporting power”— a nation that upholds cooperative norms and bridges institutional gaps.

This will demand a global presence and national alignment, and this is the challenge for a series of major strategies which the Government is about to publish; the upcoming National Security Strategy (NSS); the Strategic Defence Review; the reset with the European Union; the domestic industrial strategy, the international trade strategy, and finally the Comprehensive Spending Review. At this moment in the nation’s history, it is absolutely vital that these documents are woven together to explain a plan to do five things;

1. Defence. In defence, we have serious challenges to fix; the UK has just one division capable of sustained conventional combat, limited air defence, and munitions stockpiles insufficient for NATO’s expectations. If we are to step up a credible UK response to Russian incursion - and help secure Ukrainian victory - then we are going to need to invest in everything from submarine tracking in the North Atlantic to long-range missile strikes and evacuation operations - capacities that are currently underdeveloped or overstretched .

Crucially, we must take some decisions about how much strategic autonomy to now seek from the United States.

We have been pushing (alongside France) for integrated air, sea, and intelligence operations, yet this is “greatly dependent” (the words of IISS) on U.S. targeting, intelligence, and space capabilities. While the UK has just launched its own military satellite ( Tyche, launched by Elon Musk’s SpaceX), we are deeply reliant on U.S. space infrastructure for GPS, surveillance, and cyber-intelligence.

Cybersecurity is a similar picture. Adversaries—particularly China—are exploiting vulnerabilities to place destructive malware implants into critical infrastructure as part of strategic military planning while the UK’s National Cyber Force depends heavily on U.S. leadership to tackle problems like ransomware.

2. Industrial Policy. If Britain want to shape the post-hegemonic landscape we are going to have to invest in space, intelligence, and rapid-deployment capabilities. This will be expensive. Hence the importance of an industrial strategy that genuinely grows our economy faster, and offers a new economic model to replace the economic muddle of the last Government.

This will require an approach better targeted at grand challenges (not unwieldy missions), building stronger, more capable economic institutions in finance and research, better use of government procurement to support industrial development, and crucially, a government that is better able to row together. Whitehall must slough off much of the work that can be done far better by local government and metro-mayors, reversing the hopelessly dysfunctional centralisation of power in recent years.

3. Trade Strategy. Absolutely key to accelerating growth is the agreement of the most ambitious possible reset with the EU to offset the huge economic damage of Brexit. In turn, this may enable a concerted effort to use our leadership of CPTPP to grow the family of nations across Asia-Pacific locked into a low tariff, high standard international trade agreement (starting with Indonesia). We should add to this a joint effort to build out space at the World Trade Organisation to renew it for those, who unlike the United States, wish free trade to grow.

If we can ink deals with the Gulf Cooperation Council, Switzerland and India as well, then the UK could emerge as the hub of the one of the most powerful sets of trade alliances across the world, tied together by an ambitious set of defence partnerships - from Euro NATO, to GCAP-Tempest, to the Five Power Defence Alliance, Five Eyes, and our Strategic Partnership Council with Saudi Arabia.

4. Development/ global institutions. Fourth, in the field of development, there is a clear opportunity for the UK, together with our European allies and Japan to expand the work of the World Bank and the IMF - building stronger not weaker institutions - in contrast to the suggestion posed by Scott Bessent this week, or shrinking their role. There are plenty of ways to do this, as I have set out elsewhere.

5. Soft power projection. Finally, if the United States is going to withdraw from its role as the world’s leading defender and promotor of liberal values, then frankly we should step into the breach. As the home of the BBC, some of the greatest universities in the world, the mother of parliaments, the English language, the best music in the world, and some of the best sports teams on the planet, we are uniquely placed to tell an inspiring story from these ‘isles of wonder’ about the virtue of a liberal democracy by and large, at ease with itself.

Conclusion

In the absence of U.S. hegemony, the burden of order will fall on capable, committed mid-sized powers. Countries like the UK, France, Germany, Japan, Australia, and India must lead not as substitutes for a superpower, but as stewards of a fragile but necessary international architecture.

Britain’s history—imperial, diplomatic, multilateral—makes it unusually suited to this role. The stakes are clear.

What replaces America will be shaped either by those who coordinate—or those who coerce. The vacuum left by the US strategic retreat will not remain empty for long. If the world’s responsible powers fail to act, the vacuum will be filled by transactionalism, fragmentation, or force. But if we act now—through a modern concert of power rooted in shared interests, credible institutions, and adaptable diplomacy—we can shape a new era of order without domination.

In a divided but interdependent world, the task is not to salvage the past but to design a post-hegemonic future. That begins with coalition-building, not nostalgia. It is what you might call progressive realism.

Note: This piece was inspired by one of our seminars at St Antony’s College, University of Oxford on ‘Multilateralism in the Age of Populism’ with Prof Ngaire Woods and Lord Mark Malloch Brown, co-chaired with Rt Hon John Glen MP. I am very grateful for Ngaire, Mark, John and everyone who participated for the inspiration.