Polish President Karol Nawrocki will not attend the Ukraine Recovery Conference in Poland this week as he had not received an invitation, senior presidential aide Marcin Przydacz said on June 22."The president wasn't invited, so... he's not going to the event, to which he wasn't invited by Prime Minister Donald Tusk," Przydacz said during a press briefing, adding that none of Nawrocki's staff members are set to attend either.The presidential aide said he hopes that during the conference, Tusk would focus on "Poland's interests, rather than just raising money for Volodymyr Zelensky."The Ukraine Recovery Conference, co-hosted by Ukraine and Poland in Gdansk on June 25–26, aims to mobilize economic support and investment for Ukraine.Preparations unfold against a backdrop of sharply deteriorating relations between the two neighbors over historical grievances.The Ukrainian Presidential Office said that the issue of the invitation for Nawrocki is an internal Polish affair."It wouldn't be appropriate for us to invite the president of Poland to an event in a Polish city; it's an internal political matter," presidential advisor Dmytro Lytvyn told journalists. According to Lytvyn, Zelensky is still considering whether to attend the conference in person.A diplomatic row between Kyiv and Warsaw broke out after Zelensky named a military unit after the World War II-era Ukrainian Insurgent Army (UPA), prompting Nawrocki to strip his Ukrainian counterpart of Poland's highest state award.While Ukraine underscores the UPA's legacy of resisting Moscow's occupation, in Poland, the group is remembered chiefly as the perpetrator of the 1943-1945 Volyn massacres, mass killings of Poles in what is today western Ukraine, then under Nazi occupation.Thousands of Ukrainians were killed in retaliatory attacks, with the Volyn massacres remaining one of the most painful chapters in the Polish-Ukrainian history.The dispute is taking place a year before the Polish parliamentary elections, where Tusk's centrist government is set to face a challenge from conservative and far-right parties.Tusk, a political rival of Nawrocki, called the Ukraine-Poland dispute a "strategic mistake," urging a de-escalation of tensions.