The European Commission on Wednesday laid out the basis to set up a special court to investigate and prosecute Russia for crimes of aggression against Ukraine.

The EU executive arm also outlined how Russian assets – frozen from Western sanctions – can be used as a possible source of funding to rebuild Ukraine.

“Russia’s horrific crimes will not go unpunished,” Ursula von der Leyen, president of the commission, said in a video on Twitter to announce the move, recalling alleged atrocities discovered in the Kiev suburb of Bucha.

While backing the International Criminal Court’s (ICC) investigations of Russia for war crimes, among other things, the commission wants to set up an alternative means of investigating Russian crimes of aggression.

This is due to the ICC’s lack of competence to prosecute the offence as Russia does not recognize the court’s jurisdiction in this legal area, an options paper sent to EU member states said.

Instead, the commission wants to set up an international tribunal on the basis of a multinational treaty.

Another option would be to establish a so-called hybrid tribunal based on Ukraine’s national laws and integrate it into international procedures with international judges involved to investigate crimes of aggression.

Both possibilities for a tribunal to prosecute Russia for crimes of aggression would need to require backing from the United Nations, the commission said.

“Russia must also pay financially for the devastation that it caused.

“The damage suffered by Ukraine is estimated at 600 billion euros.

“Russia and its oligarchs have to compensate Ukraine for the damage and cover the costs for rebuilding the country,” von der Leyen said.

According to the commission, 300 billion euros (310 billion dollars) in assets from the country’s central bank reserves have already been frozen in EU and G7 countries, along with 19 euros billion in private funds frozen in the EU.

Private frozen assets can only be confiscated only in connection with a criminal offence.

EU member states on Monday approved however new rules to make sanctions evasion a crime.

A proposal to further define the offence and its penalties are planned for Friday, an EU official said.

Further challenges arise in relation to Russia’s central bank reserves, the bulk of frozen assets, as these funds need to be repaid to Russia once the sanctions are lifted under international law.

Von der Leyen wants to manage the frozen assets with proceeds going to Ukraine for reconstruction as long as sanctions are in place.

In the long term, the commission is exploring potentially linking lifting sanctions on Russia’s central bank to Russia committing to reparations for damages in Ukraine.