“It is Ukraine’s firm belief that the accountability efforts should also include the prosecution of the leadership of the Russian Federation for the crime of aggression," said Ukraine's representative to Eurojust Myroslava Krasnoborova. "The impunity for this supreme international crime should never be accepted.”

The new International Center for Prosecution of the Crime of Aggression, which should be operational by the summer, will “support and enhance investigations into the crime of aggression by securing key evidence and facilitating case building at the earliest possible stage,” Eurojust said in a statement.

It remains unclear when and where a prosecution for aggression could happen. The International Criminal Court, which is investigating in Ukraine, does not have jurisdiction. Krasnoborova said “all options are on the table” for a possible venue.

Ukraine’s first lady, Olena Zelenska, on Wednesday called on the United Nations to set up an aggression tribunal.

She is not alone. The European Union’s legislature passed a non-binding resolution in January calling on the 27-nation bloc to work “in close cooperation with Ukraine to seek and build political support in the U.N. General Assembly and other international forums ... for creating the special tribunal for the crime of aggression against Ukraine.”

Amid the international efforts to ensure accountability, Ukrainian prosecutors are working on thousands of cases in their country.

Krasnoborova said Ukrainian authorities already are investigating the crime of aggression and Ukrainian prosecutors have registered more than 71,000 alleged war crimes since the war began. She said 99 cases have been sent to courts and 26 verdicts have been reached.

Eurojust also said Thursday that it has formally opened a digital database for evidence of war crimes and other atrocities committed in Ukraine.

“This database is a real game changer in the prosecution of international crimes," Eurojust President Ladislav Hamran said.

Eurojust already is facilitating the work of a Joint Investigation Team made up of prosecutors from seven nations including Ukraine that also cooperates with the International Criminal Court prosecution office, which opened its own investigation in Ukraine almost a year ago.

The investigation team's efforts in The Hague are part of a broader hunt across Europe for accountability for war crimes in Ukraine. Prosecutors in Poland, Germany, Lithuania, Latvia, Estonia, France, Slovakia, Sweden, Norway and Switzerland have opened investigations of their own.