Kyiv has said it has identified more than 10,000 possible war crimes.

Shishimarin, from Siberia, had said he was acting on orders and had asked his victim’s widow to forgive him, telling the court he was pressured into an act for which he was “truly sorry”.

“I was nervous about what was going on. I didn’t want to kill,” he said as the trial concluded on Friday.

His lawyer had argued for an acquittal, saying his client was carrying out what he perceived to be a direct order that he initially disobeyed.

Prosecutors, who had asked for a life sentence, said he was “well aware” he was executing a “criminal order”.

Speaking via video link, and receiving a standing ovation, he said the world cannot be ruled by “brute force” and “maximum sanctions” should be imposed on Russia.

Tens of thousands of lives would have been saved, he said, if Kyiv had received “100 per cent of our needs at once, back in February” when Ukraine was invaded.

“This is why Ukraine needs all the weapons that we ask (for), not just the ones that have been provided,” said Zelensky, flanked by Ukrainian flags.

He called for an oil embargo on Russia, punitive measures against all its banks and the shunning of its IT sector, adding that all foreign companies should leave the country.

“There should not be any trade with Russia. I believe there are still no such sanctions against Russia, and there should be.”

Russian business and political leaders, who once took part in debates and mingled with other A-listers at champagne parties, were barred from this year’s gathering, dubbed “History at a Turning Point”, over the war.

A strong Ukrainian contingent, including the foreign minister, made the journey to Davos in person to plead their country’s case.

02:26

Russian soldier pleads guilty in Ukraine’s first war crimes trial

Russian soldier pleads guilty in Ukraine’s first war crimes trial

“The major request to the whole world here is: do not stop backing Ukraine,” said Ukrainian lawmaker Ivanna Klympush-Tsintsadze on the eve of the summit.

More than 50 heads of state or government are among the 2,500 delegates, ranging from business leaders to academics and civil society figures.

On Sunday, Polish President Andrzej Duda, whose country is a vital staging area for Western arms shipments and host to millions of the war’s refugees, pointed to the devastation in Ukraine’s cities as a reason for why “business as usual” with Russia was no longer possible.

“An honest world cannot return to business as usual while forgetting the crimes, the aggression, the fundamental rights that have been trampled on,” he told Ukraine’s parliament.

US President Joe Biden echoed Duda’s firm tone on Monday, telling a Tokyo press conference Russia had to “pay a long-term price” for its “barbarism in Ukraine” in terms of sanctions imposed by the United States and its allies.

Three months after launching an invasion that failed in its initial goal of capturing Kyiv, Moscow’s forces are now squarely focused on securing and expanding their gains in the Donbas region and on Ukraine’s southern coast.

After 3 months of war, life in Russia has profoundly changed

But as its relentless offensive continues, Russia’s lead negotiator said on Sunday that Moscow was willing to resume negotiations with Ukraine, which it blames for “freezing” earlier talks.

Any talks, however, will not include concessions of land, according to Zelensky’s chief of staff Andriy Yermak, who tweeted that the war must end with “complete restoration of (Ukraine’s) territorial integrity”.

In the eastern city of Severodonetsk, a focus of recent fighting, regional governor Sergiy Gaiday said Russian forces attempting its encirclement were “using scorched-earth tactics, deliberately destroying” the city.

Gaiday said Russia was drawing forces from a vast area – those withdrawn from the Kharkiv region, others involved in Mariupol’s siege, pro-Russian separatist militias, and even troops freshly mobilised from Siberia – and concentrating their firepower on the Donetsk and Luhansk regions.

The volunteers from Belarus, Russia’s ally, fighting for Ukraine

At least seven civilians were killed and eight others wounded in Sunday’s bombardment of the Donetsk region, according to the Ukrainian army’s Facebook page.

Shelling and missile strikes also continued to pound Kharkiv in the north, as well as Mykolayiv and Zaporizhzhia in the south, Ukrainian officials said.

With the nation under relentless assault, Ukraine’s parliament on Sunday voted to extend martial law until August 23, while millions of ordinary Ukrainians face a daily struggle to survive.

“There is no work, no food, no water,” said Angela Kopytsa, 52, breaking down into tears as she spoke to Agence France-Presse reporters on a Russian-organised tour of captured port city Mariupol.

She said her home had been destroyed and “children in maternity wards were dying of hunger”.

Once-bustling Mariupol has been reduced to a wasteland of charred buildings.

Additional reporting by Reuters