EU enlargement: renewed debate amid geopolitical shifts

Enlargement, the process of integrating new member states into the European Union (EU), is widely regarded as the EU’s most powerful foreign policy tool. Over the decades, it has shaped the Union’s geopolitical landscape, expanded its economic reach, and reinforced democratic values across Europe.

The first enlargement took place in 1973 with the accession of the United Kingdom, Ireland, and Denmark. Greece followed in 1981, Spain and Portugal in 1986, and Austria, Sweden, and Finland in 1995. The 2004 accession of ten countries—often referred to as the "Big Bang" enlargement—marked the EU’s most significant enlargement in terms of both population and the number of new members. The most recent enlargement occurred in 2013 when Croatia joined, marking the longest period without expansion since the first enlargement.

Stagnation in enlargement policy

Following the "Big Bang" enlargement, the EU’s enlargement policy entered a period of stagnation, driven by multiple factors. The integration of ten new countries fuelled debates over the Union’s "ultimate borders" and its capacity to absorb new members. The concept of "enlargement fatigue" has increasingly shaped public opinion and influenced political leaders across Europe, as evidenced by the failed referenda on the EU Constitutional Treaty in the Netherlands and France in 2005.

Moreover, governance issues in some new member states—particularly regarding democracy and the rule of law—exposed weaknesses in the EU’s enlargement strategy. Meanwhile, crises such as the global financial crisis, the irregular migration influx, and the rise of populism pushed enlargement further down the EU’s priority list. Jean-Claude Juncker¹, President of the European Commission from 2014 to 2019, explicitly stated that no new members would be admitted during his tenure.

Russia’s war in Ukraine: a turning point

Russia’s invasion of Ukraine in February 2022 marked a pivotal moment for the EU, compelling it to reassess its enlargement policy. Just four days after the war began, Ukraine formally applied for EU membership, with Moldova and Georgia following suit shortly after.

These unprecedented applications reignited the stalled enlargement process. The EU responded swiftly, granting Ukraine and Moldova candidate status and expediting their applications. However, controversial legislation on foreign influence and family values has triggered developments that have effectively brought Georgia’s EU accession process to a swift de facto standstill.

This renewed momentum has also had ripple effects on the Western Balkans, a region long sidelined in the enlargement process. Recognising the rising influence of China and Russia, as well as shifts in Europe’s security landscape, the EU has sought to re-engage with the region. It introduced the €6 billion Growth and Reform Plan to support Western Balkan economies. Yet, despite these efforts, progress remains uneven. While Bosnia and Herzegovina and Albania have taken steps in their accession paths, other Balkan countries remain in limbo, hindered by regional tensions, inter-ethnic conflicts, and unresolved disputes with some EU member states. Montenegro’s EU accession process is progressing more favourably, positioning it as the frontrunner to potentially become the next member of the EU.

The war in Ukraine has not had a tangible impact on Türkiye’s EU accession process either, which remains stalled due to longstanding challenges and political obstacles related to the Cyprus issue.

Challenges on both sides of enlargement

Enlargement is a two-sided process. On one hand, candidate countries must meet the EU’s stringent requirements; on the other, the EU itself must be politically and institutionally ready to expand.

Most candidate countries still face significant challenges in aligning with EU standards. Issues such as corruption, weak rule of law, human rights concerns, and unresolved territorial conflicts hinder their progress. The outcome of the war in Ukraine remains uncertain, and the normalisation of Serbia-Kosovo relations remains elusive. Additionally, public support for EU accession varies widely across candidate countries, further complicating the process².

Within the EU, enlargement remains a politically sensitive issue. Membership requires unanimous approval, yet many member states are increasingly sceptical due to concerns over migration, economic disparities, and governance standards. The rise of nationalist and populist movements has further fuelled opposition to enlargement.

Moreover, enlargement does not just help to transform the candidate countries—it also reshapes the EU itself. The Union admits the need for proper preparation for the financial, political, and governance implications of integrating new members. Maria Dumoulin³ warns that delays in the enlargement process, combined with ongoing debates over internal EU reforms, undermine the credibility of membership prospects, reducing incentives for candidate countries to pursue necessary reforms.

The shift toward gradual integration

Recognizing that full accession will take time, the EU is adopting a gradual integration approach. This strategy allows candidate countries to participate in key EU policies—particularly the Single Market—as they progressively align with the EU acquis. However, whether this approach will be enough to keep aspiring members committed to the EU path remains uncertain.

Frank Schimmelfennig⁴ argues that differentiated integration could offer a viable solution. Under this model, dedicated candidates could secure membership more quickly, but their full rights and benefits would remain conditional on continued institutional progress. However, if gradual integration leads to prolonged delays, it could erode credibility, weaken candidate countries' trust in the EU, and push them to seek alternative alliances.

Conclusion: a delicate balancing act

As the EU navigates an increasingly complex geopolitical landscape, it must strike a careful balance between ambition and realism in its enlargement policy. To maintain credibility and uphold its values, the EU must adopt a fair, transparent, and balanced approach. Ensuring that commitments are realistic and achievable will be crucial in sustaining trust among candidate countries and reinforcing the EU’s long-term stability and influence. Otherwise, the entire enlargement policy could collapse, jeopardizing the EU’s credibility, unity, and geopolitical influence.