Millions of Ukrainian refugees are likely to remain in the European Union for years – and possibly permanently – even if the war with Russia ends, according to a new report by Dutch think-tank Clingendael Institute that warns European governments must prepare for long-term integration rather than assume a rapid mass return home.

The report, "Between War and Return: Scenarios for the Future of Ukraine and Its Refugees", outlines four possible futures for Ukraine between 2026 and 2030 and analyses how each could reshape migration flows across Europe.

“The report concludes that in all scenarios a large number of Ukrainian refugees – including those in continued need of protection or in need of an alternative status after TPD ends – will likely remain in the EU for many years, if not permanently,” the study said, referring to the EU’s Temporary Protection Directive (TPD).

“Russia’s full-scale invasion of Ukraine in February 2022 not only led to the largest and most destructive war in Europe since World War II, but also led to the continent’s biggest displacement crisis since that time,” the report said. More than 5.9mn Ukrainian refugees were recorded outside the country by January 2026, according to figures cited in the report.

The Clingendael study was published as uncertainty grows over the future trajectory of the war and the prospects for refugee return. US President Donald Trump has pushed diplomatic initiatives aimed at ending the conflict, but the report noted that “Donald Trump’s fervent diplomatic offensive” had produced “few tangible results”.

The authors said policymakers needed to prepare for multiple possible futures rather than rely on assumptions about a quick end to the conflict or a swift repatriation of refugees.

“As such, this report is an exercise in strategic foresight, which is a systematic analysis of plausible futures,” the paper said.

The study presents four scenarios ranging from continued war with Ukrainian territorial gains to a Russian military advance, and from fragile ceasefires to a more stable post-war recovery backed by Western security guarantees.

In the first scenario, Ukraine manages to regain parts of the east and south while the war drags on. Economic recovery remains weak, but the improved security situation encourages many displaced Ukrainians to return.

Under this outcome, the number of Ukrainians requiring protection in the EU would fall from around 4.3mn to between 2.4mn and 2.7mn.

The second scenario paints a far darker picture. Russian forces achieve major territorial advances, recapturing the entire Donbas region and pushing closer to major Ukrainian cities including Kharkiv, Dnipro and Zaporizhzhia. The report said this would trigger a new wave of mass migration into Europe.

“This scenario leads to large new displacements of Ukrainians, with 7.1 to 11.7mn more Ukrainians fleeing to the EU,” the study said. Under that scenario, the number of Ukrainians needing protection inside the EU could rise to between 9.3mn and 13.9mn people.

The third scenario envisages a ceasefire without a meaningful peace settlement or major economic recovery. Fighting decreases substantially, but Russia continues hybrid pressure on Ukraine while political conditions inside the country deteriorate. As a result, many refugees would remain reluctant to return despite the reduction in violence.

“This scenario leads to limited further displacement,” the study said, while warning that “the disappointing economic and political situation in Ukraine leads to limited return migration”.

Around 2.4mn Ukrainians would still require protection in the EU under this outcome, while many others would shift from temporary protection to permanent or longer-term residency arrangements.

The fourth and most optimistic scenario assumes a stable ceasefire combined with strong Western security guarantees and deep institutional reform inside Ukraine. “In this scenario, there is no new displacement of Ukrainians nor forced emigration out of Ukraine,” the report said. 

The study estimates that around 2.5mn Ukrainians currently under temporary protection in the EU would return home in that case. However, the report said large numbers would still stay in Europe permanently.

“Even in the most positive scenario, in which the war ends with a robust ceasefire and Ukraine achieves a substantial economic recovery … no more than 2.5mn BTPs are expected to return, while more than a million Ukrainians whose TPD status has expired are expected to remain in the EU,” the study said.

The report stressed that ending active fighting alone would not be enough to trigger mass refugee returns. “A third key conclusion of this report is that an end to the active fighting through a ceasefire is an insufficient condition for Ukrainian refugees to return in large numbers,” the authors wrote.

Instead, return decisions would depend heavily on the durability of any ceasefire, Ukraine’s security environment, economic opportunities and political trajectory after the war.

“Once the war ends, the prospects for refugee return will also be determined by the nature of the ceasefire and the robustness of Ukraine’s resulting security, the level of economic recovery that will take place, and the political developments in post-war Ukraine,” the report said.

The study warned that Ukraine’s demographic challenges were becoming increasingly severe after years of war, migration and population decline.

Before Russia’s full-scale invasion, Ukraine’s population was estimated at around 41mn. By the end of 2025, only about 31mn people remained in government-controlled areas, according to figures cited in the report.

The authors said many of the war’s demographic effects were likely irreversible. “The war against Russia is transforming Ukraine’s economy, geography, demographics, politics, and society,” the report said.

“Key features of this change are the country’s demographic decline, forced international migration, the demographic and economic shift from the east to the west of the country, the decline of traditional industries and employment models … and the rise of new industries.”

The report also highlighted the risk that some of the most vulnerable Ukrainians could become trapped in dangerous frontline areas because they lack the means to leave.

“Contrary to what one might expect, those Ukrainians who are hit the hardest by adverse and deteriorating conditions … are typically the least mobile,” the study said.

Demographic forecasts cited in the report suggest Ukraine’s population could shrink to between 24mn and 35mn by 2050 depending on how the war develops and how much migration continues.

The study cited Ukrainian demographer Ella Libanova as saying Ukraine would require hundreds of thousands of immigrants annually just to stabilise its population.

Against that backdrop, the authors argued that EU governments needed to shift towards long-term planning for Ukrainian refugees already living in Europe.

“This means that EU member states, including the Netherlands, need to start planning to facilitate the longer stay of Ukrainian refugees who cannot return in the near future,” the report said.

The paper also warned that if legal protections expire without replacement arrangements, many refugees could struggle to remain legally inside the EU.

“The end of the TPD (without similar alternatives), for example, would lead many Ukrainian refugees to apply for alternative statuses in their respective host countries,” the study said.

“If they are unable to do so, the refugees in question would more likely move out of the EU and towards other host countries … or resort to illegality rather than return en masse to Ukraine.”

The report concluded that European governments needed clearer long-term strategies both for integration and for legal residency pathways.

“In order to avoid such a turn towards illegality,” the authors wrote, “the EU member states should develop specific plans to allow Ukrainians who are unable to return to remain in their host countries for a longer period of time.”