Ukraine's President Volodymyr Zelensky speaks during a press conference as part of the European Council meeting in Brussels on December 18, 2025. JOHN THYS / AFP

Ukrainian President Volodymyr Zelensky told EU leaders on Thursday, December 18, that they had the "moral" and legal right to use frozen Russian assets to fund Kyiv, as pressure grew on key player Belgium to drop its opposition at a summit showdown.

The 27-nation bloc is scrambling to bolster its ally Ukraine, as US President Donald Trump pushes for a deal with President Vladimir Putin to end the fighting.

Officials have insisted leaders' talks in Brussels will last as long as it takes to hammer out an agreement, saying both Ukraine's survival – nearly four years into the war – and Europe's credibility are at stake. "We will not leave the European summit without a solution for the funding of Ukraine," European Commission head Ursula von der Leyen said.

The EU's executive wants to fund a loan to Ukraine by using frozen assets from Russia's central bank, though it is holding on to a back-up plan for the bloc to raise the money itself. The EU estimates Ukraine needs an extra 135 billion euros ($159 billion) to stay afloat over the next two years – with the cash crunch set to start in April.