The United States fully backs the European Union using frozen Russian assets as a tool to support Ukraine and end the war with Russia, a US source familiar with the situation told Reuters on Friday.

As the West seeks to ramp up pressure on Moscow, the European Commission has proposed a plan allowing EU governments to use up to €185 billion ($217 billion) – most of the €210 billion worth of Russian sovereign assets currently frozen in Europe – without confiscating them.

Washington “absolutely supports (the EU) and the steps they’re taking right now to be in a position to make use of those assets as a tool,” the source said, requesting anonymity to discuss an ongoing issue.

After Russian President Vladimir Putin sent troops into Ukraine in 2022, the United States and its allies prohibited transactions with Russia’s central bank and finance ministry, immobilizing around $300 billion of sovereign Russian assets.

The European proposal is being held up due to concerns from Belgium, where most of the assets are located.

Germany suggested on Friday that recent drone sightings over airports and military bases in Belgium were a message from Moscow not to touch the frozen assets. Moscow has denied any connection to the incidents and has promised a “painful response” if its assets are seized.

In a renewed attempt to end Russia’s war, US President Donald Trump hit Rosneft and Lukoil, its two biggest oil companies, with sanctions late last month, adding to an unprecedented basket of economic sanctions that seek to pressure Moscow and those doing business with it.

The move underlined Washington’s intent to squeeze Russia’s finances and force the Kremlin towards a peace deal in its three-and-a-half-year-old full-scale invasion of Ukraine.

Washington is watching the fallout from the Rosneft and Lukoil move and “there are more things we could do to try to up the pressure,” the source said.