In the wake of Brexit and the UK’s evolving global role, establishing an external association with the United States merits serious consideration. Historical precedents, such as Scotland’s 1707 union with England and Éamon de Valera’s concept of Irish external association, suggest that this framework could provide the UK with economic stability and strategic alignment while addressing pressing challenges.
The Acts of Union Treaty of 1707 illustrates how economic hardship, instability, and security concerns can drive integration. Given the UK’s current economic fragility and strategic uncertainties, deeper cooperation with the US presents an appealing long-term option.
Strengthening economic ties with the US could yield substantial benefits, including increased trade, improved market access, and secured investments in key sectors like technology, pharmaceuticals, and finance. This could stabilize the UK’s financial services sector and help maintain London’s status as a global financial hub.
An external association could formalize the UK-US “Special Relationship,” building on existing partnerships like NATO and the Five Eyes alliance. This would enhance the UK’s defense capabilities, particularly in cybersecurity and AI, while amplifying its geopolitical influence in the Indo-Pacific region and solidifying its role as a key Euro-Atlantic player.
The specifics of such an arrangement would depend on shared interests and various domestic and international considerations. However, there is significant potential for mutual benefit, as the colonial histories of both nations offer valuable lessons for shaping a UK-US External Association that leverages their synergies.
Before Brexit, the UK was one of the three leading economic and political powers in the EU, alongside France and Germany, granting it significant influence within the bloc. It had the strongest military in Europe, supported by nuclear capabilities, and held a permanent seat on the UN Security Council (UNSC).
As the hub for the Commonwealth of Nations, the UK leveraged its economic appeal and soft power to build strong relationships with member states, positioning itself favorably with the USA, often being the first stop for US Presidents engaging with Europe. However, this influence diminished with the decision to exit the EU in 2016, finalized in 2020.
In December 2024, the UK sought to address this decline by formally joining the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP), an Indo-Asia Pacific economic bloc, becoming the second-largest economy in the grouping after Japan. However, the short-term gains from this accession are marginal, as the UK already had trade deals with most CPTPP nations through its EU membership, such as with Singapore. Unlike the EU, the CPTPP lacks a single market for goods and services, meaning regulatory harmonization is not required.
Since Brexit, the UK has added Australia and New Zealand to its trade agreements, but the expected gains from these accords are small, estimated at around 0.08% of GDP over ten years. In contrast, independent forecasters suggest that leaving the EU could reduce the UK’s growth by as much as 4% of its income. In 2019, the CPTPP accounted for only 8% of UK exports, less than the sales to Germany alone.
Despite these economic challenges, the strategic implications of CPTPP membership are significant, as the UK can influence whether applicants like China and Taiwan may join the group. However, this occurs amid ongoing questions about the UK’s economic malaise, political uncertainties, and the relative decline of its global standing as a middle power.
The UK’s global role remains debated, with no clear narrative emerging. To move forward, London must confront significant challenges. While some factions tout the UK’s ‘superpower’ status, it is increasingly seen as a middle power with notable influence but also significant vulnerabilities.
Shifting global power dynamics have diminished the UK’s status as a Great Power. The economic rise of Brazil, China, and India has eroded its influence, and the power of international institutions like the UN has also declined. If Great Power status is defined as being among the top five influential nations, the UK no longer qualifies. Even in a broader definition of the top ten, its position appears precarious and unlikely to last beyond the mid-21st century.
Despite this, the UK retains characteristics of a great power, driven by a geopolitical mindset focused on defending its interests, even at the expense of global norms. While its military, industrial, and economic powers have declined, the UK remains a significant player in Europe, demonstrating a commitment to a rule-based order, particularly in defending the freedom of the seas.
However, the UK’s tough stance on security relations with China conflicts with its goal of promoting commercial ties in the Indo-Asia Pacific. This tension is complicated by the need for a united Western alliance, while ongoing frictions with the EU risk reinforcing the perception of the UK as an outlier among its allies.
Despite these challenges, the UK’s defense posture remains anchored in the Euro-Atlantic region, with a strong military presence in the Middle East and Africa, second only to its NATO commitments. This reflects the UK’s continued great power mindset as it seeks to shape the rules and norms governing the international system.
Views on the UK’s declining status as a Great Power have been expressed since 2015 and were further crystallized in the 2021 paper, “The Integrated Review: The UK as a Reluctant Middle Power?”, which acknowledges the UK’s middle power status, albeit one with substantial clout.
The UK exerts global influence through its permanent UNSC seat, status as a nuclear power, and leadership in the G7, G20, Commonwealth, and NATO. Its involvement in AUKUS, a trilateral defense pact with the US and Australia, and the Five Power Defence Arrangements in Southeast Asia underscores its strategic and diplomatic reach. Additionally, London’s role as a “global conductor of offshore jurisdictions” reinforces its position as a leading financial hub.
These positions grant the UK leverage beyond its individual capabilities, further enhanced by its new membership in the CPTPP. In many ways, the UK is poised to occupy a niche similar to Japan as a “network power.” According to Mireya Solis of the Brookings Institution, Japan’s status as a network power is supported by its resilience, social stability, and adaptability, allowing it to build flexible partnerships in international relations.
The UK’s strengths in these areas suggest it can leverage its network of relationships to achieve its goals. To maintain its influence, the UK must either adapt its ambitions to this new reality or take concrete steps to bolster its position. One potential solution could be forming an external association with the US to enhance its global influence and strengthen ties with its enduring ally.
A formalised UK-US external association, potentially as a confederation, federal union, or associated statehood, offers significant mutual benefits. Such an arrangement could enhance investment, deepen market access, and strengthen strategic cooperation across key sectors.
Closer alignment would likely boost bilateral trade and investment in technology, finance, and pharmaceuticals, granting the UK preferential access to US markets and alleviating some of the economic challenges posed by Brexit. This partnership could provide a framework for sustained economic growth and geopolitical collaboration while redefining transatlantic ties in a rapidly shifting global landscape.
The UK and US already collaborate extensively through NATO and the “Five Eyes” intelligence alliance. A formalized association could deepen this partnership, enhancing the UK’s global security role and driving advancements in defense technologies, cybersecurity, and AI. This alignment would also allow the UK to leverage America’s global influence to amplify its foreign policy objectives, particularly in countering China’s rise as an economic competitor and systemic rival to the EU.
Moreover, a UK-US association would promote economic stability, especially for the City of London, as the UK navigates its post-EU future. Closer financial integration with the US could increase American investment in the UK, strengthen supply chains, and ensure reliability in critical sectors. The interdependence between London and New York City, which are already the dominant axis in global finance, would further entrench their control over financial flows and technology.
Culturally and historically, the ties between the UK and US make closer alignment feasible. Shared language, legal traditions, and historical connections provide a strong foundation for a deeper partnership. A united front would enable both nations to promote democratic systems, free trade, and international norms, reinforcing their leadership roles on the global stage.
However, a UK-US association carries significant risks. The perception that British sovereignty is being compromised for US interests could provoke domestic resistance, particularly among those wary of over-reliance on the US. Concerns over sovereignty contributed to Brexit, and an inequitable arrangement could see the US dictating terms, undermining the UK’s negotiating power and strategic autonomy.
Additionally, closer ties with the US could strain the UK’s fragile relationship with the EU, complicating trade and political cooperation. This shift may also affect the UK’s global image, especially among Commonwealth nations and non-aligned states, who might view it as prioritizing US interests over multilateralism. Aligning with US economic policies could necessitate regulatory changes that conflict with UK interests in areas like data privacy and food standards.
Furthermore, this association could exacerbate tensions with rivals like China and Russia, exposing the UK to increased economic and cyber retaliation. The UK’s ability to maintain independence and pursue its own interests could be compromised, potentially undermining its global influence and reputation.
Historical precedents, such as the Acts of Union Treaty 1707, illustrate how economic challenges, instability, and security concerns drive integration. Amid current global competition and uncertainties, deepening UK-US cooperation through an external association offers a viable strategy. Such an arrangement could strengthen technological and defense collaboration, expand the UK’s Indo-Pacific influence, and reinforce its Euro-Atlantic role, with shared colonial histories providing a framework for mutually beneficial partnerships.
The UK can draw insights from early 20th-century integration models. The proposed external association for Ireland sought to balance sovereignty with British ties, granting domestic autonomy while maintaining British oversight in defense and foreign affairs. Though supported during the Anglo-Irish Treaty negotiations, it was rejected, leading to Ireland’s dominion status (Irish Free State) in 1922 and eventual full independence.
The Imperial Federation, also proposed during this period, envisioned a central parliament in London to oversee trade, foreign relations, and defense, with representation from dominions like Canada and Australia, as well as crown colonies like Singapore. While dominions retained internal self-government, they were still accountable to the imperial parliament. Although aimed at unifying the empire and reducing independence demands, it was never implemented, and decolonization began in the mid-20th century.
Dominion status offered greater autonomy compared to external association, allowing nations like Canada and Australia to achieve full independence while maintaining Commonwealth ties. In contrast, external associations imposed greater restrictions, limiting sovereignty in defense and foreign policy.
The US’s Compacts of Free Association (COFA) with the Marshall Islands, Micronesia, and Palau illustrate how structured partnerships, defined as associated statehood, can balance sovereignty and strategic alignment. These agreements provide US support in defense, finance, and immigration while securing military access and diplomatic influence. Renewed in 2023 for 20 years, COFA demonstrates how such models can counter global competition, like China’s influence, without colonial overtones.
Similarly, the UK’s approach during its EU membership (1973–2020) highlights how opt-outs and shared competences can maintain policy autonomy while benefiting from cooperation. Key opt-outs included staying outside the Eurozone and Schengen Area, maintaining border controls and the pound sterling, and selectively engaging in Justice and Home Affairs. The UK also retained autonomy in defense policy and limited the EU Charter’s application domestically.
Shared competences allowed collaboration in areas like the internal market, environmental policy, agriculture, transport, energy, research, and regional development. These frameworks balanced integration with sovereignty, offering valuable insights into structuring cooperative arrangements that meet mutual strategic goals while respecting national autonomy.
The idea of the UK forming an external association with the United States is intriguing, particularly post-Brexit, as the UK seeks to maintain its global influence. However, the viability and benefits of such an arrangement depend on shared interests, specific terms, and both domestic and international dynamics.
During its EU membership, the UK’s opt-outs—such as retaining the pound sterling, maintaining border controls, and limiting EU jurisdiction in justice and defense—allowed significant autonomy while shared competences enabled collaborative policymaking in areas like market integration and environmental standards. This approach reflected the UK’s preference for balancing sovereignty with selective integration, offering lessons for any potential US partnership.
An external association with the US could deliver economic growth, technological innovation, and security benefits, but it raises complex political, legal, and sovereignty issues. The UK and US already share robust bilateral ties in defense, economics, and global initiatives, which may suffice to achieve mutual goals without formalizing the relationship. Strengthening transatlantic trade and leveraging frameworks like NATO and AUKUS may be more practical alternatives.
Targeted collaboration on global challenges, such as climate change and technology governance, could also enhance UK-US relations. However, navigating US isolationist tendencies and domestic opposition in both countries presents significant challenges. The UK must weigh the risks of aligning too closely with US policies, including potential sovereignty compromises, a power imbalance, and tensions with the EU and Commonwealth.
To mitigate these risks, the UK should adopt a balanced approach. Drawing from models like the US Compacts of Free Association or historical integration frameworks, the UK could craft a mutually beneficial partnership that safeguards strategic autonomy. Ultimately, this underscores the need for a reassessment of the UK’s global strategy, focusing on nuanced international cooperation that aligns with its national interests in an evolving global landscape.