Rethinking Enlargement for a New Age of the EU

Rethinking Enlargement for a New Age of the EU

A Policy Proposal for Layered Geopolitical Integration

Written By Gidi Brandes

EXECUTIVE SUMMARY

EU enlargement is no longer just a question of whether candidate countries are legally and institutionally ready for membership. It has become a geopolitical question about how the Union organizes security, markets, infrastructure, and political order across a wider Europe. The older enlargement model was built around conditionality: countries adopted EU rules in exchange for the prospect of full membership. That model helped drive earlier rounds of enlargement, but it was designed for a less adversarial strategic environment. Recent research shows that the war in Ukraine has pushed enlargement back to the centre of European politics, while also exposing the mismatch between geopolitical urgency and the EU’s slow, legally demanding accession machinery (Karjalainen, 2023; Koval & Vachudova, 2024; Scicluna, 2025).

This brief argues that the EU should not choose between being “bigger” and being “better.” It should instead become better at being selectively bigger. Full accession should remain the endpoint for countries that satisfy the Copenhagen criteria, but the Union should add a more systematic second track of sector-specific participation before membership. Under this model, candidate states, and, in carefully defined areas selected strategic partners, could join specific EU mechanisms in diverse policy areas without immediately becoming full members.

INTRODUCTION AND OBJECTIVE

The purpose of this proposal is to rethink enlargement as a broader strategy of European integration rather than a single institutional gate. In the classic post-Cold War model, enlargement worked because the EU could rely on what Schimmelfennig and Sedelmeier (2004) called “governance by conditionality”: the Union extended rules, candidates complied, and membership functioned as the reward for transformation. That approach gave the EU a powerful tool for exporting standards and stabilizing its neighbourhood. Yet it assumed that external transformation and internal enlargement could proceed in a relatively orderly, linear fashion. That assumption is much harder to sustain today, when the EU faces war instability

and uncertainty, with growing pressure to shoulder more of its own defence and resilience burden.

The objective here is therefore not to dilute accession or to replace it with a vague partnership model, but to reconcile two facts that now coexist uncomfortably. The first is that full membership remains the EU’s most important external incentive and its strongest instrument of long-term transformation. The second is that Europe’s strategic needs increasingly require deeper cooperation with non-members before full accession is either politically or institutionally feasible. A viable policy has to respect both facts at once. That is why this brief proposes a layered enlargement framework in which accession and early policy participation operate in parallel rather than as mutually exclusive alternatives.

CONTEXT AND BACKGROUND

TABLE 1. Current EU Context for the Enlargement Debate

Source Note: Based on Council and Commission pages current as of April 2026

The immediate background to this debate is the return of hard geopolitics to Europe. Karjalainen (2023) argues that wartime enlargement has emerged from the interaction of geopolitical pressures, state-building challenges, and the EU’s own internal constraints. Koval and Vachudova (2024) likewise argue that the EU’s future as a geopolitical actor is closely tied to the credibility of a revived enlargement process. In other words, enlargement now matters not only because it rewards reforms, but because it shapes the political and security order of Europe itself. This shift has been especially visible since Russia’s full-scale invasion

of Ukraine, which made the old practice of leaving neighbouring states in prolonged grey zones look strategically dangerous rather than merely procedurally slow.

Official EU practice already shows the strain on the older framework. The Council currently lists nine candidate countries (Table 1). The same Council page still presents accession through the familiar sequence of application, candidate status, negotiations, and full membership. Meanwhile, the Commission’s Ukraine accession page notes that accession negotiations with Ukraine formally opened on 25 June 2024 and that the screening of negotiating chapters was completed on 30 September 2025. These are major political steps, but they also highlight the problem: even where the strategic case for integration is unusually strong, the accession framework remains slow, sequential, and legally demanding.

At the same time, European nations have begun creating institutions and instruments that stretch beyond the binary logic of membership. The European Political Community was explicitly designed as a forum for broader political dialogue and cooperation across the continent without replacing enlargement. In defence, the evolution is even more significant. The Commission’s 2025 White Paper for European Defence states that the EU will promote “open architecture” and “variable geometry” so that like-minded partners can participate in cooperative projects on a case-by-case basis. SAFE pushes that logic further: the Council describes SAFE as a loan instrument of up to €150 billion for common procurement, while also stating that Ukraine and EEA/EFTA countries may participate with member states on equal terms in common procurements, and that Canada and other eligible partners can participate under specified conditions. The EU has therefore already moved, in practice, toward a wider strategic space than full membership alone can capture.

RESEARCH AND FINDINGS

The literature suggests that the problem is not simply that enlargement has slowed down. It is that the EU’s legal model of enlargement has remained binary while its functional model of integration has become increasingly differentiated. Lavenex (2011) described the EU’s external governance as a set of concentric circles rather than a firm territorial boundary.

Schimmelfennig (2016) developed this logic further through the idea of graded membership, showing how states that are unwilling or unable to assume full membership can still occupy meaningful in-between positions. Emerson et al. (2021) apply that logic directly to enlargement by proposing staged accession as a way to revive incentives while addressing member-state concerns about institutional overload. The analytical point is straightforward:

differentiated participation is not alien to the EU as it is already one of the ways the EU manages complexity.

More recent work shows that this logic is becoming increasingly important because the rationale of enlargement itself has changed. Anghel and Jones (2024) argue that enlargement is moving from a club logic toward a broader geopolitical commons. Ghincea and Pleșca (2025) explain this shift in terms of changing policy logics, moving from transformation toward demarcation and geopolitical ordering. Scicluna (2025) adds that the post-2022 debate is now framed simultaneously by geopolitical drivers and procedural roadblocks. Together, this suggests that the EU wants enlargement to do more strategic work than its current accession machinery can deliver. A policy redesign is therefore not optional but the logical consequence of the tension between the EU’s strategic ambitions and its institutional form.

The literature on integration capacity helps explain why simple fast-tracking is not a sufficient answer. Börzel, Dimitrova, and Schimmelfennig (2017) show that enlargement debates are inseparable from questions of institutional absorption, distributive effects, and political legitimacy within the Union itself. That point matters because many member states do not reject enlargement in principle; they worry about unmanaged enlargement. A model that collapses strategic urgency into immediate membership risks worsening exactly those tensions. This is also why Amadio Viceré and Bonomi’s argument that external differentiation can function as a strategy of system maintenance is so useful: it suggests that the EU can widen meaningful cooperation without prematurely widening full membership.

Finally, the Western Balkans literature shows why flexibility must not mean weaker standards. Richter and Wunsch (2020) argue that rampant state capture limited the impact of EU political conditionality in the region. Hoxhaj (2021) similarly shows that EU rule-of-law initiatives faced serious obstacles where domestic political conditions were unfavourable to real transformation. Hogic (2024) goes further by arguing that the EU’s narrow focus on the judiciary overlooked the wider social and economic preconditions of the rule of law. These findings do not undermine enlargement but sharpen it. They show that earlier participation can only be credible if it is linked to sector-specific benchmarks, close monitoring, and genuine reversibility.

TABLE 2. Classical Enlargement vs. Layered Enlargement

Source note: Author’s comparison based on Schimmelfenig (2016, 2019), Lavenex (2011), and Emerson et al. (2021)

POLICY OPTIONS AND ITS DISCONTENTS

One option would be to preserve the classical accession model unchanged. Its virtue is clarity. It protects the legal seriousness of membership, avoids inventing new categories of partial inclusion, and keeps the Copenhagen logic intact. Yet it is increasingly misaligned with the EU’s strategic environment. If the Union’s only serious offer remains eventual full membership after a long and uncertain process, it will struggle to integrate strategically vital states in time-sensitive sectors such as defence, cyber resilience, energy connectivity, or industrial production. The existing model remains necessary, but on its own it is too rigid for current conditions.

A second option would be to fast-track full membership for strategically important candidates. This option has obvious political appeal, especially in relation to Ukraine and Moldova, because it offers a strong geopolitical signal. It also fits the argument that the EU’s geopolitical credibility depends on the credibility of enlargement. But the risks are substantial. Fast-tracking can confuse urgency with preparedness and may intensify internal disputes over voting rules, funds, rule-of-law enforcement, and institutional balance. Scicluna’s analysis is especially helpful here: the war has revived enlargement politically, but procedural roadblocks have not disappeared. Fast-track membership therefore promises decisiveness, but it may actually produce new forms of backlash and instability.

A third option would be to rely primarily on looser political formats such as the EPC. This is better than strategic exclusion because it creates channels for dialogue and political coordination. But it remains too shallow. The EPC is intentionally light and explicitly not a substitute for accession. It does not organize deep policy participation, bind access to specific benchmarks, or integrate outsiders into functional EU mechanisms at the level needed in defence, infrastructure, digital standards, or market preparation. Diplomacy matters, but diplomacy without structured participation will not solve the problem this brief addresses.

The most plausible option is therefore a layered enlargement model. This approach preserves full membership as the endpoint for candidates, but introduces structured participation before membership in specific policy fields. Its main risk is that intermediate participation could become a permanent waiting room or generate new hierarchies between insiders and outsiders. That risk is real. But it is manageable if the EU links access to clear sectoral benchmarks, regular review, reversible suspension, and an explicit distinction between candidates on a membership path and strategic partners for whom membership is not the relevant endpoint. Compared with the alternatives, this option best aligns the Union’s geopolitical needs with its institutional realities.

TABLE 3. Actor-by-Actor Policy Participation Matrix

H = strong fit | S = selective/conditional fit | L = limited fit | N = not applicable before membership

Source Note: Illustrative proposal, informed by current EU defence and enlargement practice, including SAFE and the 2025 White Paper for European Defence

FIGURE 1. From Binary Accession to Layered Enlargement

Source Note: Author’s Synthesis on Staged Accession and Differentiated Integration arguments in Schimmelfenig (2016), Lavenex (2011), and Emerson et al. (2021)

POLICY RECOMMENDATIONS

The EU should formally adopt a dual-track enlargement framework. Classical accession should remain the first track and continue to govern the route to full membership. Alongside it, the EU should establish a second track of sector-specific participation before membership. That second track should not be framed as a consolation prize. It should be presented as a deliberate instrument of geopolitical integration that allows the Union to widen cooperation where urgency is greatest while preserving the constitutional and distributive safeguards attached to full accession. This is most urgently needed in defence, where the White Paper and SAFE already provide the foundations for variable-geometry cooperation with non-members.

This new track should begin with sectoral participation compacts. Defence should come first, covering procurement, military mobility, cyber cooperation, defence-industrial production, and selected capability projects. Energy and infrastructure should follow, especially where interconnection and corridor-building directly support resilience. Digital governance and selected industrial policies should also be included, because strategic autonomy increasingly links security policy to economic and technological capacity, as Juncos and Vanhoonacker (2024) show. The principle should be simple: where common risks are already shared, common mechanisms should begin earlier.

Access to these compacts must be conditional, benchmarked, and reversible. The Western Balkans experience shows why this is essential. Earlier participation should not come with

automatic voting rights, unrestricted budgetary claims, or blanket institutional inclusion. Instead, it should be tied to measurable standards in the relevant sector and suspended when democratic backsliding, sanctions evasion, or major policy divergence occurs. At the same time, candidates must not be left in permanent limbo. For states with a genuine accession perspective, participation compacts should feed into formal accession progress through regular review and published progression reports. That is the only way to make a layered model both geopolitically useful and politically credible.

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