The European Union has said experts had agreed on the "legal foundations" for a special tribunal to try Russia over the war in Ukraine.
Proposals for establishing a court to hold Russia accountable over its invasion were floated more than two years ago.
However wrangling over the legal basis for the tribunal and how it would work has meant progress on establishing it has been painfully slow.
The return of US President Donald Trump to the White House appears to have sped up efforts, as European officials fear his plans for a peace deal could mean Moscow escapes justice for good.
The EU said experts from 37 countries meeting in Brussels had "laid down the legal foundations for the establishment of a Special Tribunal for the Crime of Aggression against Ukraine".
They also set out the key elements of the legal text that would govern how the court functions, Brussels said.
"When Russia chose to roll its tanks over Ukraine's borders, breaking the UN Charter, it committed one of the gravest violations: the Crime of Aggression," European Commission president Ursula von der Leyen said.
"Now, justice is coming. Justice for Ukraine."
EU justice commissioner Michael McGrath said that some technical work remained to draw up a final draft but he hoped it would be concluded in the near future.
While talks have dragged on over the tribunal, the International Criminal Court in March 2023 issued an arrest warrant for Russian President Vladimir Putin over the abduction of Ukrainian children.
But the special tribunal is specifically intended to try Russia for the "crime of aggression", for which the ICC does not have jurisdiction.
In a bid to hold Russia accountable, Ukrainian and international investigators have continued efforts to document thousands of cases of abuses committed during the war.
Ukraine has said that it is probing over 140,000 cases of potential war crimes in the country.
In a related push to try to make Russia pay for the damage it has wrought in Kyiv, the EU also proposed joining possible talks on an "International Claims Commission" for Ukraine.
Five Ukrainians killed in Russian missile attack
Meanwhile, a Russian ballistic missile strike has killed five people - including a pregnant teenager - and wounded more than four dozen others in the east Ukrainian town of Izyum, officials said.
President Volodymyr Zelensky said after the attack that it was "impossible to reconcile with this cruelty" and urged allies to pile pressure on Moscow to end its nearly three-year invasion.
Oleg Synegubov, governor of the wider Kharkiv region, said 55 people had been wounded in the Russian strike, and that two young women were among the dead.
"They were 18 and 19 years old and one of them was pregnant," he wrote on social media.
An AFP journalist at the scene saw tearful women consoling each other after identifying one of the victims laid out in a body bag lined up by police.
Larysa Chygrynets was at work in the local tax office when she heard the air raid siren sound and then the missile strike seconds later.
"Everything was covered in blood and the windows were smashed," the 51-year-old said of the scenes in her office.
She said that life in Izyum some 40 kilometres from the front line had been relatively calm and that residents had been returning.
"Everything was calm, nothing indicated trouble. We thought everything would be fine by now. But you can see what they have done," she said.
Mr Zelensky said the city council building had been damaged in the attack while Synegubov earlier said a five-storey residential building was hit.
"We need to put pressure on Russia, use as much force as possible - the force of arms, the force of sanctions, the force of diplomacy - to stop the terror and protect lives," Mr Zelensky wrote on social media.
Izyum, which had a population of around 45,000 people before the Russian invasion launched in February 2022, was occupied for several months at the beginning of the war before being retaken by Ukrainian forces later that year.
Russian forces are making gains in the region and undoing the advances Kyiv's army made in their 2022 counteroffensive, while stepping up bombardments.
