Marco Siddi
Leading Researcher
Finnish Institute of International Affairs
Finland
Associate Professor
University of Cagliari
Italy
Poland has been a major supporter of Ukraine after Russia’s invasion in February 2022. However, shortly after his election as president of Poland in June 2025, Karol Nawrocki declared that he opposed Ukraine’s accession to the European Union. A key reason for his stance, as he argued, was the existence of unresolved “important civilisational issues” between Poland and Ukraine. Nawrocki referred to the massacres of an estimated 100,000 Polish civilians in Volhynia and Eastern Galicia (in today’s Western Ukraine) by Ukrainian nationalists in 1943.
These events have been studied extensively by a group of historians including Grzegorz Motyka, Andrii Portnov, Grzegorz Rossolinski-Liebe and Timothy Snyder, among others. Summarizing a complex story, in early 1943 the leadership of the Ukrainian nationalist organisation OUN/UPA decided that Volhynia and Eastern Galicia should be cleansed of ethnic Poles. By doing this, they hoped to ensure that these regions would not become part of Poland after the Second World War (as they were in the interwar years).
The brutal killings of Polish civilians were preceded – and followed – by a series of events that feature in current controversies. The Organisation of Ukrainian Nationalists (OUN) was founded in 1929 and operated in interwar Poland with a strategy of violence and terrorism, inspired by Italian fascism and German national socialism. In the 1930s, Poland was an authoritarian state that often trampled minority rights and aimed to Polonise the eastern ‘border’ regions (Kresy). Even so, OUN remained a relatively small and marginal political force until the war.
The Nazi occupation of Poland in 1939 favoured OUN leaders, who were hosted and supported financially by the occupying Germans in the city of Krakow – while they were repressed in the eastern Polish regions occupied by the Soviets in 1939-1941. The Nazi invasion of the Soviet Union in 1941 seemed to provide an opportunity to OUN, whose militias seized control of numerous settlements and participated in anti-Jewish pogroms. While Nazi Germany rejected OUN’s calls for an independent Ukrainian state, OUN militias enlisted in the German-controlled Ukrainian Auxiliary Police and played a vital role in the execution of the Holocaust in 1941-1942. Following the German defeat at Stalingrad, Ukrainian nationalists left en masse the auxiliary police and swelled the ranks of the newly-founded Ukrainian Insurgent Army (UPA), which swiftly turned against Volhynian Poles in spring-summer 1943.
UPA’s massacres were followed by retaliatory murders of ethnic Ukrainians conducted by the Polish Home Army in 1943 (with an estimated 10-15,000 dead), mutual deportations from the border regions conducted by communist Poland and the Ukrainian Soviet authorities in 1944-46, and the deportation of post-war Poland’s remaining Ukrainians to the west and north of the country during Operation Vistula in 1947.
During state socialism, the memory of these events – including the Volhynian massacres – was marginalised in both the Soviet Union and Poland. After 1989, democratic Poland’s acceptance of the post-1945 eastern borders seemed to pave the way for reconciliation, as shown by the first joint Polish-Ukrainian commemorations of the Volhynian massacres in 2003. However, developments took a different turn.
While the Polish side expected official apologies and the designation of UPA as the main perpetrator, the Volhynian massacres remained marginal in Ukrainian official discourse, where events were portrayed as a two-way slaughter. Post-Euromaidan Ukraine fully rehabilitated the UPA and other nationalist groups, drawing parallels between their anti-Soviet struggle in the 1940s and the ongoing Ukrainian fight against Russian invasions in 2014 and 2022. One of the four memory laws adopted by Ukraine in 2015 listed OUN/UPA among ‘independence fighters’ and forbade the ‘public expression of derogatory attitudes’ towards them.
In 2016, the Polish parliament adopted a resolution recognising UPA’s crimes in Volhynia as genocide. In 2018, it passed legislative amendments including a sentence of up to three years in jail for denying or belittling the Volhynian massacres. Representatives of Poland’s then national conservative government declared that Warsaw would make its agreement to Ukraine’s EU accession conditional on condemnation of UPA. This stance was widely endorsed by the post-2023 centrist Polish government, while the oppositional far-right party Confederation stoked the memory conflict through chauvinist narratives. Russia reportedly fomented the clash through agents provocateurs that defaced memory monuments.
Despite this, there has been some room for reconciliation in Ukrainian and Polish official memories. Russia’s full-scale attack on Ukraine in 2022 led to a temporary ‘memory rapprochement’, as highlighted by the joint commemoration of the Volhynian massacres held in Lutsk in July 2023, attended by presidents Volodymyr Zelensky and Andrzej Duda. Ukraine (re)allowed exhumations of Polish soldiers, which had been suspended in 2017.
Yet, the broader divergence of views on UPA and Volhynia remains unsolved. Despite overwhelming evidence of UPA’s criminal actions, Ukraine has chosen to honour its fighters. Meanwhile, the relevant Polish debate is ever more politicised. In July 2025, the Polish Sejm voted almost unanimously in favour of creating a day of remembrance of victims of genocide committed by OUN-UPA in the ‘eastern borderlands’ of interwar Poland, to be held annually on 11 July. Ukraine harshly criticized the decision. Most worryingly, the protracted conflict between official memory narratives is contributing to an atmosphere of resentment, especially toward the large community of Ukrainians living in Poland while war rages in their country.