Both Washington and Brussels have come out in favour of using Russian assets frozen by sanctions to finance Ukraine's resistance or rebuilding but doing so is likely to be a legal minefield that could take years.
European Council President Charles Michel told the Interfax-Ukraine news agency on Thursday that he is "absolutely convinced that this is extremely important not only to freeze assets but also to make possible to confiscate it, to make it available for the rebuilding of the country".
He then acknowledged that seizing the assets of sanctioned individuals “is not so simple” and that it would likely be "a difficult and long process" and said he's instructed the European Council's legal service to look into it.
His comments came about a week after US President Joe Biden called on Congress to expedite legislation to confiscate and sell off property of sanctioned individuals to "help build Ukraine".
The American Civil Liberties Union, a nonprofit organisation that aims to defend rights granted by the US Constitution, warned however that it would be "unconstitutional". Other legal experts have issued similar reservations about the plans.
Hundreds of billions of euros frozen
"We are into kind of unprecedented territory here," Ian Bond, director of foreign policy at the Centre of European Reform (CER), a think tank, stressed to Euronews.
Yet, he added, "there are some prospects that eventually Ukraine might be able to extract some money from these frozen assets. But it would be really, really complicated and probably take a very long time."
Theoretically, assets frozen because of sanctions could remain frozen indefinitely. Unfreezing them would either require the sanctioned individual or entity to successfully challenge the order in court or victims to mount their own legal battles to receive some of the frozen assets as compensation.
In the case of Ukraine, Western countries have sanctioned both Russian state agencies, officials and state-owned companies as well as oligarchs and private businesses they say have helped Moscow finance and wage its bloody invasion.
It is hard to quantify just how much has been frozen although it is estimated that $300 billion (€283 billion) of the Russian Central Bank's foreign reserves have been frozen around the world.
The EU announced in early April that its Task Force had frozen assets worth €29.5 billion, including boats, helicopters, real estate and artwork, and blocked about €196 billion of transactions.
The UK has meanwhile said it has frozen £500 billion (€583 billion) from Russian banks or businesses, some of them partly state-owned, with an additional £150 billion (€175 billion) of oligarchs and their family member's assets also frozen.
State assets vs individuals' assets
"I think it's much easier for Ukraine or individual Ukrainians who have suffered as a result of this war to take action to get hold of state assets," Bond explained, "because there's such a clear connexion between the decisions and the actions of the state and its agents and the assets that have been frozen."
"The whole thing becomes a lot easier if the International Criminal Court does find that Russia has committed genocide or crimes against humanity. If you are either the Ukrainian state or individual Ukrainians, you've got a judgement from the International Criminal Court that says a terrible wrong has been done to you -- the most serious wrongs that can be committed by a state -- then it's a bit easier to start going to other jurisdictions and other courts and saying: 'We want to enforce this judgement'," he went on.
The Russian Central Bank is reportedly looking into legal action to recover its foreign reserves, although the fact that they are held in a lot of different jurisdictions will make it harder.
Brussels makes such challenges particularly hard, according to Bond.
"In the EU case, you probably go to the European Court of Justice. The experience of individuals who have tried to get sanctions against them lifted, generally in relation to support for terrorism, is that you will find it quite hard to win.
"And you'll find it extremely hard, even if you do win, to get your assets unfrozen because what the Commission tends to do in those circumstances is to reformulate the basis for freezing the assets to meet the objections that the court has raised rather than handing the assets back," he said.
But while European, American or Ukrainian authorities may be able to mount legal battles to confiscate these frozen state assets to help Ukraine rise from the ashes of war, it will undoubtedly be much harder to claim the assets of oligarchs and their family members. The burden of proof there is likely to be much more difficult to meet.
"To prove a link between the criminal actions in Ukraine and somebody's yacht is quite hard to do," Bond highlighted.
Ukrainian President Volodymyr Zelenskyy affirmed earlier this week that the country will need at least $600 billion to rebuild.