Europe’s enlargement moment: a historic test the EU cannot afford to fail

For years, the problem with EU enlargement was not only a lack of cohesion or collective will. It was also the absence of political appetite to confront what enlargement truly requires: not only the adaptation of candidate countries to the EU’s legal and regulatory acquis, but also the Union’s own capacity to reform itself. 

Enlargement has always exposed one of the EU’s central political difficulties. 

Externally, the Union must prove it can act credibly toward its partners. Internally, it must show that opening up to new members can generate reform, prosperity and stability rather than institutional paralysis.

Yet political momentum never followed. The Western Balkans, in particular, were left in a waiting room, trapped in what has often been described as the logic of the “Restern Balkans” – a selective and controlled enlargement process that prioritised countries seen as more economically prepared or strategically convenient. 

Slovenia moved first, followed by Romania and Bulgaria, whose full integration into Schengen came only recently, and then Croatia in 2013.

War has changed the enlargement debate

Today, the context has changed radically. The turning point came on 24 February 2022, when Russia launched its full-scale invasion of Ukraine and brought war back to the heart of Europe. 

For the first time in the EU’s history, enlargement is no longer only a question of reform, markets or institutional alignment. It has become part of Europe’s security strategy and its defence of democracy.

As of 2026, Ukraine, Moldova, Serbia, Montenegro, Albania, Bosnia and Herzegovina, and North Macedonia are all seeking to join the European Union, while Kosovo has applied but has not yet obtained candidate status. These countries carry complex and often painful histories. From the states born out of the dissolution of socialist Yugoslavia and scarred by the wars of the 1990s, to Ukraine, now fighting for national survival while pursuing difficult internal reforms. 

Moldova, meanwhile, continues to face Russian interference and the unresolved question of Transnistria.

But it would be a mistake to see the renewed enlargement debate only through the lens of Ukraine and Moldova. The credibility of the entire process will depend on whether the EU can offer concrete prospects to the Western Balkans as well. 

A successful enlargement policy must allow for different speeds of progress without creating new political fractures or new dividing lines across the region.

Enlargement is not only about borders

The value of enlargement cannot be measured only in terms of border security. It must also be understood through the economic, institutional and social opportunities it can create in candidate countries, where many citizens — especially younger generations — still see Europe as a promise of stability, development and democratic belonging.

Recent summits, including the meeting in Tivat, Montenegro, and the gathering in Sarajevo where the European People’s Party reaffirmed its support for enlargement, show that the political mood has shifted. Enlargement is now back among the priorities of the European Commission and several influential Member States.

France and Germany are also moving more visibly into the debate. A recent Franco-German non-paper, promoted by Emmanuel Macron and Friedrich Merz, starts from the premise that the EU faces a historic opportunity to complete the European project. 

It proposes making accession faster and more effective by focusing on substantive reforms in candidate countries rather than allowing the process to be blocked by procedural obstacles.

The case for gradual integration

The most innovative element of this approach is the idea of gradual integration. Candidate countries would be rewarded for concrete progress in accession negotiations by gaining phased access to EU programmes such as Erasmus+ and Horizon Europe, parts of the Single Market, and certain EU decision-making mechanisms.

Full membership would remain the final objective. But the path toward it would become more credible, more visible and more tangible for citizens. This would help prevent enlargement from becoming an abstract promise endlessly deferred, while strengthening the EU’s ability to project stability and influence in its neighbourhood.

For this to work, however, the burden cannot fall only on candidate countries. The EU must also confront its own readiness to enlarge. That means taking seriously the so-called fourth Copenhagen criterion – the Union’s capacity to integrate new members.

A larger EU will need to reflect pragmatically on institutional functioning, the distribution of competences, and how to ensure that smaller states retain an effective role in decision-making.

The cost of absence

The risk of losing momentum is clear. As Christian Schmidt, High Representative for Bosnia and Herzegovina since 2021, has warned, less Europe in the Western Balkans inevitably creates more space for other actors. 

Russia’s influence in Serbia and parts of Bosnia and Herzegovina, as well as China’s growing role in energy, infrastructure and transport, show how quickly strategic vacuums can be filled.

In this context, infrastructure, connectivity, energy security and transport links are not merely economic questions. They are strategic ones. Across parts of the Western Balkans, political and institutional obstacles continue to slow essential investments, weakening the region’s integration into the European economic space and increasing its vulnerability to external influence.

Bosnia and Herzegovina remains particularly central. Any challenge to its territorial integrity would not only destabilise the country itself, but risk undermining the wider security architecture of the Balkans.

A larger Union will change Europe

Enlargement will also force the EU to think seriously about how its institutions will function in a larger Union. Ukraine is the clearest example. With a population of around 36 million, it would send a delegation to the European Parliament comparable in size to Poland’s. This would bring into the EU institutions political perspectives shaped by war, eastern border security and the long-term consequences of Russian aggression.

The accession of the Western Balkans would also carry major social and political significance. It would deepen Europe’s engagement with societies where Muslim communities form important parts of the population, particularly in Bosnia and Herzegovina, Albania, Montenegro, North Macedonia and Kosovo. 

This could open new spaces for interreligious dialogue, political integration and coexistence within the European project.

Europe must be present on the ground

The success of enlargement will not depend only on negotiations between governments. European institutions will need to be more present in candidate countries and more directly engaged with their citizens, especially younger generations.

In a period marked by political distrust, disinformation and geopolitical competition, the European project cannot remain confined to technical chapters and diplomatic communiqués. It must become visible in the communities that aspire to join it.

Enlargement is therefore not only a question of borders, security or geopolitics. It is a choice about Europe’s identity and its ability to complete the project of a free, stable and democratic continent.

That is why enlargement is not just another item on the EU agenda. It is Europe’s appointment with history — and one it cannot afford to miss.