The European Union is studying the feasibility of using billions of euros worth of Russian central bank assets already frozen by member states to help with Ukraine’s reconstruction efforts, according to people familiar with the matter.

The discussions are at an early stage and legal experts have been recently tasked to look into possible options, the people said, asking not to be identified discussing confidential matters. Assessing whether or how to take control of the assets is extremely complex and potentially legally fraught.

But as Russia’s invasion of Ukraine drags into its ninth month and rounds of sanctions fail to deter Russian President Vladimir Putin, even as they damage his economy, the EU executive in Brussels is exploring ways to permanently cut off his access to these funds.