“We respect one another and defend from Russian imperialism together. Each resolved bilateral issue is a blow to Moscow,” wrote Ukraine’s Andrii Sybiha on the X platform on Friday.

The exhumation of some of the estimated 100,000 Polish civilians killed in a World War II-era ethnic cleansing on what are now western Ukrainian territories has long been a divisive subject in Polish Ukrainian relations.

Poland considers the killings an act of genocide while Ukraine insists it was a part of a ‘symmetrical’ armed conflict.

On Friday, Poland’s PM Donald Tusk posted on X: “Finally, a breakthrough. There has been a decision on the exhumation of the first Polish victims of the UPA. I thank the culture ministers of Poland and Ukraine for [their] good cooperation. We await further decisions.”

The deal, brokered by Warsaw’s and Kyiv’s ministries of culture, marks a major moment in the complicated history of the Polish-Ukrainian relations, and is the first real sign of progress since Kyiv banned Warsaw from conducting exhumations in 2017.

Ukraine’s decision to ban Poland’s Institute of National Remembrance (IPN) from conducting work on its soil came in response to the dismantling of a monument commemorating the Ukrainian Insurgent Army, or UPA, a military fraction remembered for its war-time resistance in Ukraine, and for its involvement in the cleansing in Poland.

The issue of the exhumations has since become a major talking point in Polish political discourse with some feeling that Ukraine should revisit its past and allow the exhumation work, especially in light of Ukraine's ambitions to join the European Union and NATO – and Poland’s upcoming presidential elections.

Karol Nawrocki, Poland’s far-right's candidate who heads the IPN, said in an interview that Ukraine had no place in NATO or the EU until it had resolved the issue as “a country that cannot answer for a very brutal crime against 120,000 of its neighbors cannot be part of international alliances.”

The comments drew condemnation from both sides of the border with the Ukrainian foreign ministry describing Nawrocki’s remarks as “biased and manipulative.”

Poland’s center-right presidential candidate Rafał Trzaskowski wrote: “it is better sometimes to hold back on some statements, instead of giving fodder to Kremlin propagandists in search of votes,” referring to gathering support in the elections, and jabbing at his main opponent in the race for Poland’s top job.