On 28 February 2022, four days after the full-scale Russian invasion, Ukraine applied for EU membership. From Kyiv, President Volodymyr Zelensky called for immediate admission through a “special procedure” (although no such procedure exists under the EU’s accession rules), and within hours the presidents of eight member states urged an accelerated process. European Commission president Ursula von der Leyen politically endorsed the idea that Ukraine “belongs to the European family”.

This came just four days after the full-scale invasion, closing a trajectory that had begun at least in 2013, when then-president Viktor Yanukovych’s decision not to sign the EU Association Agreement triggered the Euromaidan protests. In the crackdown and clashes, dozens of demonstrators were killed in Kyiv; part of Ukrainian society was literally paying with its life for the idea of “Europe” as a political and moral destiny, not merely a socioeconomic direction.

A decade-long journey

Beyond cooperation under the European Neighbourhood Policy, European integration has long been presented in Kyiv as a promise of modernisation and an escape from post-Soviet stagnation, often invoked by pro-European parties during election campaigns. For many European capitals, however, Ukrainian ambitions — intensified after the Orange Revolution in 2004 — had to be managed carefully and represented a delicate geopolitical and institutional risk, especially in the early 2000s when relations with Russia were seen as essential by several member states. The famous remark in 2002 by then European Commission president Romano Prodi, who said Ukraine had “the same chances of joining the EU as New Zealand”, neatly summed up the scepticism of that era.

The year 2014 marked a first turning point: the EU-Ukraine Association Agreement was signed in two stages (March and June 2014) and fully entered into force only on 1 September 2017, because of unexpected public resistance in the Netherlands. It included a Deep and Comprehensive Free Trade Area (DCFTA), aligning large parts of Ukrainian legislation and standards with those of the EU. In the same decade came another concrete symbol, long awaited by millions of Ukrainians: since June 2017, Ukrainian citizens with biometric passports have been able to travel visa-free for short stays (90 days within any 180-day period) in the Schengen area, with the usual EU exceptions.

Yet until 2022, membership remained more of a horizon than a timetable. In its 2022 assessment, the Commission linked progress to structural reforms on the rule of law, corruption and oligarchic influence, recognising advances but also pointing to systemic fragilities. In the background was the so-called enlargement fatigue, which followed the Big Bang enlargement of 2004 and was reinforced by the economic crisis and austerity years after 2008; the last accession remains Croatia in 2013. It was only after Russia’s invasion that Ukraine’s prospects became more concrete: enlargement, after all, is first and foremost a political decision.

Progress and obstacles

Accession is not a discretionary political “reward”; its framework is set by the treaties. Article 49 of the Treaty on European Union allows any European state that respects the Union’s values to apply, after which a long process begins, guided by Commission assessments and unanimous decisions by member states. The substantive compass is the “Copenhagen criteria”, defined in 1993: stable democratic institutions and rule of law, including respect for human rights and minorities; a functioning market economy; and the capacity to take on the obligations of membership, meaning the adoption of the EU acquis (the political and legal heritage of European integration) and the ability to cope with internal market competition.

Technically, alignment concerns the 33 chapters of the EU acquis. Under the current methodology, these are grouped into six clusters — Fundamentals; Internal Market; Competitiveness and inclusive growth; Green agenda and sustainable connectivity; Resources, agriculture and cohesion; and External relations — with a key political rule: the “Fundamentals” are opened first and closed last, as they determine the pace and credibility of the entire process.

When, on 17 June 2022, the European Commission recommended granting Ukraine candidate status, it also listed seven immediate priorities: reform of the constitutional court; continuation of judicial reform; anti-corruption measures, including the governance of SAPO and NABU; anti-money-laundering rules; implementation of the “anti-oligarch” law in line with the Venice Commission; alignment of audiovisual media legislation; and revision of laws on national minorities. In its Ukraine 2024 Report, the Commission traced the sequence leading to the formal opening of negotiations in June 2024, noting that the remaining steps had been completed and that the reforms were considered satisfactory, allowing the adoption of the negotiating framework.

The problem, however, is that the acquis requires years of screening, opening and closing clusters, and above all unanimous decisions at every stage, from progress to final ratification. This is where national vetoes come in. In recent months, the most systematic opposition has come from Viktor Orbán’s Hungary, while Robert Fico’s Slovakia — another government close to the Kremlin’s positions — has tied its support to a “strict interpretation” of accession conditions. Both countries, along with far-right and populist parties across much of the EU, also warn about the allegedly unsustainable costs of Ukraine’s impact on the EU budget.

According to Roman Petrov, Jean Monnet Chair in EU law at the National University of Kyiv-Mohyla Academy, this has created a paradox: the clusters are not “officially” open, yet technical work continues informally through the so-called Lviv format, while Kyiv waits for political unanimity to turn these steps into formal negotiation stages.

That unanimity, however, may not come soon, despite a ten-point plan presented by Enlargement Commissioner Marta Kos and Ukrainian Deputy Prime Minister Taras Kachka to speed up reforms and unlock the clusters. “For now we have problems with a couple of countries with a clearly anti-Ukrainian stance: Hungary and Slovakia above all. These governments may change in the future, of course [Hungarian elections are scheduled for April this year, with Orbán’s party nearly ten points behind in the polls, ed.],” says Petrov. “But the anti-Ukraine wave of right-wing populist governments could also grow, even in western Europe. The countries most at risk are France and Germany.”

Options for a “light membership”

In recent months, many analysts and politicians have called for a faster, more streamlined enlargement, not only for Kyiv but also for other candidates at an advanced stage: Montenegro, Moldova and Albania — countries far smaller and less geopolitically significant than Ukraine. These hopes were revived by EU foreign policy chief Kaja Kallas, who in November said new accessions by 2030 were possible.

For Ukraine, such scenarios resurfaced during the slow and opaque peace talks between Kyiv and Moscow mediated by Donald Trump’s United States. In particular, some have floated the idea of Ukraine joining as early as 2027 as part of the security guarantees sought by President Zelensky, in the form of a “membership-lite” arrangement: technically inside the EU, but without full rights, including the veto. In a recent article, Politico’s chief EU correspondent Zoya Sheftalovich outlined five steps to make a 2027 accession feasible.

“I don’t think this is a realistic prospect,” says Petrov. “We first need to define the terms. If we are talking about full membership, as it has always been, these timelines are not feasible. By 2027 Ukraine will not manage it; negotiations have not even started because they are blocked by Budapest and Bratislava. If we refer to other formats, we must remember that there is no such thing as ‘partial membership’ without voting rights. I think these are populist narratives without any real substance. Either we talk about full membership or nothing else, because other formats simply do not exist. Treaty reforms, partly because the current system is outdated and still based on unanimity, are necessary, but it is also unrealistic to expect them soon.”

President Zelensky has said diplomatically that Ukraine will at least try to be technically ready by 2027, although the German chancellor Friedrich Merz has already ruled out any kind of light accession for any candidate state, including Ukraine. And Germany’s position still weighs heavily on the European balance.

“We face a growing tension between the time which is needed to apply a credible, merits-based approach and growing pressure from external players on our candidates – pressure intended to raise the political cost of moving forward on their EU path,” Kos said in Tallinn in early February. “Our enlargement model requires time, stability and gradual reform. But today’s geopolitical environment is unstable and often coercive,” she added, warning that any new models under consideration must start from the same baseline: “full membership comes only after full reforms.” Kos had already warned against admitting new “Trojan horses” into the Union, in order to avoid repeating the Hungarian scenario.

Reasons for caution

“As long as the war continues, accession is not possible,” says Petrov. “It is not possible for several reasons: security, economic and legal. And the member states themselves are not ready for it — to accept a country at war and therefore be responsible for its territorial sovereignty under the EU solidarity principle. Financial and military aid is one thing; sending contingents and soldiers is another. So accession is not possible while the war continues, even if some mention the Cyprus model. But the Republic of Cyprus joined the Union when fighting had been frozen for decades, with a peace plan in place and clear borders.”

However, this remains a matter of debate rather than a settled EU position. While serious political, legal and security obstacles persist, accession during wartime is increasingly framed in Brussels as an unprecedented challenge rather than an outright impossibility. Over the past year, preparations for Ukraine’s membership have moved forward on multiple tracks. The so-called “Lviv format” has allowed the other 26 member states, together with the Commission, to frontload the process: Ukraine has received detailed benchmarks and technical criteria normally delivered only during formal negotiations. The work is now underway at a granular level, with the Commission already unpacking interim and closing benchmarks on issues ranging from judicial reform to public procurement. At the same time, during her recent visit to Kyiv marking the fourth anniversary of the full-scale invasion, Commission President Ursula von der Leyen struck a cautious tone, declining to endorse Kyiv’s ambition to join the EU by 2027 and stressing that accession cannot be tied to fixed deadlines, even as Ukraine continues to push for a clear timeline.

Kaja Kallas has also said that EU governments are not ready to give Ukraine a date for membership, despite Zelensky’s request. “My feeling is that the member states are not ready to give a concrete date,” she told a panel at the Munich Security Conference. “There’s a lot of work to be done.”

According to Petrov, among the clusters currently under discussion, the one most aligned with EU standards is External relations, which covers trade policy and foreign, security and defence policy. Here, alignment is mainly political and diplomatic, based on coordination between the foreign ministry and Brussels: “it is mostly the foreign ministry’s job, harmonising our foreign policy with that of the EU”.

The picture is different in the other chapters. In the Internal Market cluster, legislative reforms are technically feasible, but may face “resistance from certain economic sectors, particularly agriculture and food”, traditionally protected by the state. The main bottleneck remains the Fundamentals cluster, covering the rule of law and corruption, where continuous reforms and tangible results will be required: “corruption continues, scandals do not disappear, and these areas will always be under the EU’s scrutiny”. The scandal last summer involving the anti-corruption bodies NABU and SAPO — which parliament had voted to place under government control, before Zelensky reversed course after mass protests — showed how fragile progress can be.

Many reforms, Petrov adds, are also difficult to implement in wartime, especially in areas such as connectivity and the green transition, which “require not only laws, but also investment and administrative capacity”.

The weight of the political context

Petrov also points to two often overlooked political factors. The first concerns the evolution of US-EU relations: any strategic divergence between Washington and Brussels would inevitably affect Kyiv, which is allied to both. In this context, the future of NATO is also uncertain. If the alliance were to weaken or transform, many EU member states could push for a common European defence, and in that scenario Ukraine — with its military experience and strategic weight — would become a highly sought-after partner.

The second, often underestimated factor is the need for internal EU reform. The current institutional architecture, based on the Lisbon treaty, is widely seen as ill-suited to a large-scale enlargement. The simultaneous accession of Ukraine, Moldova and the western Balkan countries would require deep changes, from curbing unanimity in certain areas to strengthening common policies, particularly defence. But such negotiations would be complex and politically painful among the Twenty-Seven.

In the end, Petrov agrees that “enlargement is first and foremost a political process”. Without unanimity among member states, even significant reform progress may not be enough: “these are the rules”. Every national parliament will have to ratify accession, raising difficult questions: “who will control the processes in national parliaments? And which governments will be in power when the votes take place?”

Even a strongly pro-Ukrainian country like the Netherlands experienced a controversial referendum in 2016 on the EU-Ukraine association agreement, which ended with a victory for Eurosceptics, and it still maintains a cautious stance. What might happen if such a situation were repeated, as Orbán has proposed in Hungary, or in other countries? These factors depend little on Kyiv and a great deal on domestic politics across the Union.

For Ukraine, the only option is to continue the tortuous path of reforms, with tangible efforts and achievements despite the difficulties of war, and hope for clearer skies over Brussels and the other capitals of the Twenty-Seven.