Top EU diplomat Kaja Kallas said Monday that financing Ukraine via a loan based on Russia’s frozen assets was now looking “increasingly difficult” ahead of a crunch European Council summit on Thursday.

Kallas’ warning on the narrowing path to securing a deal on Russia’s immobilized billions came as European leaders gather in Berlin to try to influence the shape of a potential peace deal in discussions with Ukrainian President Volodymyr Zelenskyy and envoys from U.S. President Donald Trump.

EU leaders including German Chancellor Friedrich Merz insist that using Russia’s frozen assets is the only credible method for Europe to keep Ukraine financially afloat from next year.

But in the run-up to the summit in Brussels, fears are growing that the push could be derailed by opposition from EU states, who are under pressure from both Russia and the United States.

While Belgian Prime Minister Bart De Wever has mentioned threats from Russia if Brussels seizes the assets — and Moscow has already taken steps to sue the Belgian bank where most of the cash is held — two senior European officials involved with the loan effort said the U.S. was also pressuring EU states to go against the scheme.

“The Americans are not only demanding that Ukraine cede territories Russia did not manage to take, but are also pushing several European countries not to give Ukraine a €210 billion reparations loan,” said one of the senior European officials.

According to a leaked U.S.-Russia draft peace plan, Washington intends to direct part of the assets toward U.S.-led reconstruction efforts, and the same European officials said the U.S. had not dropped its basic opposition to Europe using the assets to help Ukraine.

Germany’s Merz has already insisted that the Russian assets should not be transferred to America’s economic advantage.

Speaking on her way into a gathering of foreign ministers in Brussels, Kallas noted “significant pressure from all sides” over the reparations loan, which she called the “most credible option” to keep Kyiv financially afloat from next year.

“This [reparations loan] is what we’re working on. We are not there yet and it is increasingly difficult, but we’re doing the work and we still have some days,” she said.

Belgium has long been opposed to using Russia’s frozen assets to help Ukraine, arguing that this would imperil the peace process and expose Brussels to legal retaliation from Russia.

In recent days, Italy, Bulgaria and Malta came out against the scheme, while Hungary and Slovakia have previously voiced opposition. Over the weekend, Czechia’s newly-installed prime minister, Andrej Babiš, came out against the loan, saying Prague would not provide any financial guarantees to back up Belgium.

The EU doesn’t need unanimous backing to tap the assets following a decision last week to use emergency powers to immobilize the assets indefinitely. A vote by qualified majority could still pass even if all seven countries cited above oppose it, given that a blocking minority requires 35 percent of the EU’s population. 

But Kallas said that it would “not be easy” to override Belgium, given that the bulk of the assets are in the country. “I think it’s important that they are on board with whatever we do.”

The threats against Belgium appear to be ramping up.

A joint investigation by EU Observer, Humo, De Morgen and Dossier Center stated that the chief executive of Euroclear, Valérie Urbain, has been the subject of threats and intimidation from a Russia-sympathizing French banker linked to Euroclear, requiring her to contract private security.

In response, former Estonian Prime Minister Kallas said “some countries are more used to the threats presented by Russia than others — but I want to tell you these are only threats. If we keep united, we are much stronger.”