Where will Europe’s borders end? On 6 October, EU leaders convened in Granada, Spain, to discuss a question that has captivated Eurocrats, think tanks and journalists throughout the bloc since the start of the war in Ukraine.

While the European Union already granted Ukraine candidate status in June 2022, the European Council is expected to vote on beginning formal accession talks on 15 December. But the debate in Spain shows that the question is no longer really about Ukraine and the western Balkans; it is now an existential question with far-reaching implications for the EU and its role in a fast-changing global environment.

The EU appears to be moving towards radical reinvention, a ‘refoundation’ built on three pillars, each of which is the subject of fierce debate. It is looking for a grand bargain between geopolitical imperatives and liberal values.

The first pillar is security. As the EU shifts from a peace project to a war project, it is forced to reconsider some of its core assumptions. Most obviously, European leaders must give up their aversion to hard power. But it’s still unclear how this process will play out: can European governments unite and develop their own military capabilities, or will they squander their money on ready-made equipment from the United States and South Korea?

National borders, once regarded by EU leaders as malleable, have taken on a new meaning following Russia’s invasion of Ukraine. At its core, the enlargement debate is about defining the borders of the bloc’s sphere of influence, ensuring that countries like Ukraine and Moldova can pursue a European future rather than being treated as buffer states between the EU and Russia.

The EU’s shifting understanding of security underscores the significance of enlargement. Given the strategic use of immigration, energy and critical raw materials, as well as the growing nationalisation of technological innovation and regulation, member states can’t rely on NATO alone to meet all of their defence needs. Only by expanding and strengthening the EU can the safety of European citizens be ensured.

That brings us to the second pillar: the economy. Europeans, arguably more than any other group, believed in the transformative power of economic interdependence and its ability to convert erstwhile adversaries into allies. But given Russia’s weaponisation of its energy exports and China’s threats to restrict medical supplies during the Covid-19 pandemic, the EU is now pursuing greater self-sufficiency to mitigate potential risks.

But Europe can never achieve complete self-sufficiency. Instead of pursuing ‘strategic autonomy’, European leaders must focus on fostering diverse relationships with multiple partners, ensuring that we have alternatives should one country ever try to blackmail us. For example, Ukraine and the Balkans could offer critical inputs and labour, thereby helping to shore up Europe’s global standing.

But this is also where the push for enlargement might face significant opposition. On a recent visit to Warsaw, I witnessed the ramifications of the grain crisis caused by the war in Ukraine. Although Poland is a staunch advocate of Ukraine’s entry into NATO and understands the geopolitical rationale for enlargement better than most countries, it also has strong reservations. One major concern is the potential for economic upheaval that would adversely affect Poland’s agriculture sector. And then there’s the less-than-appealing prospect of Poland turning into a net contributor to the EU budget should Ukraine become a member state.

The third pillar is values. In the past, Europe was divided between the liberal cosmopolitan EU member states and those outside the bloc, which required gradual integration and transformation, one chapter of the acquis communautaire (the body of EU law) at a time. But now, this dichotomy is evident within the EU itself, with countries like Hungary and Poland embracing illiberal nationalism.

Enlargement offers a potential solution for both camps. For Europe’s liberals, it represents an opportunity to implement internal reforms through rule-of-law conditionality and qualified-majority voting. This approach would, one may hope, mitigate the nationalist tendencies that have often hindered efforts to establish a unified foreign policy. By contrast, Europe’s illiberals believe that by admitting Serbia under autocratic President Aleksandar Vucic and potentially a more nationalistic Ukraine, the collective strength of the illiberal bloc would be great enough to challenge Germany and France, the EU’s de facto leaders.

The victory of liberalism is far from guaranteed. At the moment, all eyes are on Hungary and on Poland, which will hold a critical general election on 15 October. Meanwhile, the political heirs of Benito Mussolini are already in power in Italy, and France might follow suit if Marine Le Pen wins the 2027 presidential election.

Nevertheless, Europe is on the cusp of a new era. The current situation is reminiscent of the post–Cold War years, when European leaders debated whether to enlarge the bloc or deepen its integration. Hoping to have their cake and eat it, they tried to do both. But when the Balkans spiralled into chaos, commentators drew parallels between the EU’s leadership and Nero fiddling as Rome burned. Today, the EU faces a similar danger, as profound existential dilemmas are reduced to bureaucratic debates over budgets, processes and institutions.

To thrive in a rapidly changing geopolitical environment, the EU must expand and deepen its integration. But achieving that might prove more challenging in 2023 than it was in 2004. Instead of guiding Ukraine, Moldova and the Balkans through the same accession process that Poland and Hungary undertook, the EU must create new, innovative frameworks. That may result in a messier structure of overlapping circles, rather than the Europe of ‘concentric circles’ envisioned by the bloc’s leaders. But if the European project is to survive, it must reinvent itself to find a grand bargain, not merely expand its borders.