EU foreign ministers were in the Ukrainian city of Lviv on Friday, where they are expected to endorse the creation of a special tribunal to try Russia's top leadership over the invasion.
The gathering was a symbolic show of support on the same day Russia commemorates the end of World War II with a grand military parade in Moscow, where President Vladimir Putin evoked Soviet victory over Nazi Germany to rally the country round his three-year offensive.
"It is important and symbolic that European partners stand side by side with Ukraine on Europe Day," Ukraine's Prime Minister Denys Shmygal said in a social media post.
He welcomed delegations from 35 countries and the Council of Europe, including the European Union's top diplomat, Kaja Kallas.
"There will be no impunity, there will be accountability for the crimes committed," Kallas said Thursday after a meeting of EU ministers in Warsaw.
The special tribunal is designed to prosecute Russia's top leadership for the "crime of aggression" in launching the invasion of Ukraine.
The International Criminal Court (ICC) in the Hague has already issued arrest warrants for Putin over the abduction of Ukrainian children, and four of his top commanders for targeting civilians.
But the ICC does not have the jurisdiction to prosecute Russia for the more fundamental decision to launch the invasion.
The new tribunal is not expected to be able to try Putin while he is in office due to a principle of international law that gives immunity to presidents, prime ministers and foreign ministers.
Proposals for establishing the tribunal were floated more than two years ago but wrangling over its legal basis and how it would work has made progress slow.
The return of US President Donald Trump to the White House appears to have sped up efforts, as European officials fear his plans for a peace deal could lead to Moscow escaping justice for good.
