At the same time, on the ground of military operations, Russian forces are keeping up the pressure to try to seize Bakhmout, a city in eastern Ukrainian territory in the vicinity of which fighting has been raging since summer.
"The enemy continues to concentrate its main efforts on the conduct of offensive actions in the Bakhmout sector", thus reported at the end of the afternoon the staff of the Ukrainian army.
The Russians had recently claimed the capture of three villages near this city which had 70,000 inhabitants before the war and which is now largely destroyed.
This battle took on all the more symbolic importance for Moscow as the conquest of Bakhmout, with the support of the paramilitary group Wagner, would come after a series of humiliating defeats, with the retreats from Kharkiv (north-east) in September and from Kherson (south) in November.
An employee of the Ukrainian embassy in Madrid was also slightly injured on Wednesday by the explosion of a letter bomb, leading kyiv to order a reinforcement of security in all its diplomatic representations.
"While continuing to support the International Criminal Court (ICC, headquartered in The Hague), we propose to set up a UN-backed special tribunal to investigate and prosecute Russia's crimes of aggression “against Ukraine, said the president of the European executive Ursula von der Leyen, in a video posted on Wednesday on Twitter.
A proposal that must be presented to the Member States for discussion.
The creation of such a tribunal has been demanded on several occasions by Ukrainian President Volodymyr Zelensky, as well as by the Baltic countries.
"This is exactly what we have been proposing for a long time", welcomed the chief of staff of the Ukrainian presidency, Andriï Yermak.
The ICC only has jurisdiction over war crimes and crimes against humanity committed in Ukraine and not over Russia's 'crimes of aggression', as Moscow is not a signatory to the Rome Treaty establishing the Court .
"An ad hoc tribunal with jurisdiction over crimes of aggression would allow the prosecution of Russia's most senior leaders who would otherwise enjoy immunity," the commission explained in a preliminary document.
But to set up such a court, broad international support will be needed, she acknowledges.
If the proposal has no chance of passing the UN Security Council due to Russian opposition, it may have more resonance in the General Assembly.
- Make Russia pay -
The Europeans also want to talk with their partners, particularly within the G7, about their desire to make Moscow pay for the material destruction in Ukraine.
"Together with our partners, we will ensure that Russia pays for the devastation it has caused, using the frozen funds of the oligarchs and the assets of its central bank," said Ursula von der Leyen.
EU member states have already frozen 19 billion euros in assets belonging to Russian oligarchs and some 300 billion euros in Central Bank of Russia reserves are blocked in the EU and other G7 countries .
With regard to public assets, the Commission proposes to create "a structure to manage these funds and invest them". The income thus generated could be used directly for the reconstruction of Ukraine.
Once the sanctions are lifted, these central bank assets should be returned but they could "be linked to a peace agreement to compensate Ukraine for the damage suffered".
With regard to the assets of the oligarchs which have been frozen, their confiscation would only be possible in connection with a criminal offence. The EU is in the process of harmonizing the laws of its member states in order to uniformly punish the circumvention of sanctions, which could serve as a basis for such a measure.
More than 20,000 civilians and more than 100,000 Ukrainian soldiers have been killed or injured since the start of the invasion of Ukraine in February, said the head of the European executive.
The damage suffered by Ukraine is, according to her, evaluated at 600 billion euros.
"The situation remains very difficult" in many regions in connection with the power cuts, including in the capital kyiv, for his part regretted President Zelensky on Wednesday, according to which six million of his compatriots are still without electricity in following a series of Russian strikes on energy infrastructure.
On the same day, he criticized a controversial peace plan proposal made by American billionaire Elon Musk to end the Russian offensive in Ukraine, inviting him to visit his battered country.
"And then you will tell me how to end this war, who started it and when it can be over," he said, while his Foreign Minister Dmytro Kouleba and the head of Turkish diplomacy Mevlut Cavusoglu "discussed in detail the Ukrainian peace formula" recently presented to the G20.