Russian forces on Wednesday pounded the easternmost Ukrainian-held city in the Donbas region that is now the focus of the three-month war, threatening to shut off the last main escape route for civilians trapped in the path of their advance.
After failing to seize Ukraine's capital Kyiv or its second city Kharkiv, Russia is trying to take full control of the Donbas, comprised of two eastern provinces Moscow claims on behalf of separatists.
Russia has poured thousands of troops into the region, attacking from three sides in an attempt to encircle Ukrainian forces holding out in the city of Sievierodonetsk and its twin Lysychansk. Their fall would leave the whole of Luhansk region under Russian control, a key Kremlin war aim.
"All the remaining strength of the Russian army is now concentrated on this region," President Volodymyr Zelenskiy said in a late night address.
His office said the Russians had launched their assault on Sievierodonetsk early on Wednesday and the town was under constant mortar fire.
Luhansk regional governor Serhiy Gaidai said six civilians had been killed and at least eight wounded, most near bomb shelters, in Sievierodonetsk. The main road out was still being shelled, he said, but humanitarian aid was still getting in.
Ukraine's military said fighting for the road was ongoing, and that on Tuesday it had repelled nine Russian attacks in the Donbas. It reported at least 14 civilians killed in strikes by aircraft, artillery, tanks, mortars and missiles.
'I have nothing'
In Pokrovsk, a Ukrainian-held Donbas city that has become a major hub for supplies and evacuations, a missile had blasted a crater in a railway track and damaged nearby buildings, including Lydiia Oleksiivna's house.
She was clearing dust and ash that covered her kitchen. The windows had been blown out and external walls destroyed. "I don't know if we can save the house," she said.
In Kramatorsk, nearer the front line, streets were largely deserted, while in Sloviansk further west, many residents took advantage of what Ukraine said was a break in the Russian assault to leave.
"My house was bombed, I have nothing," said Vera Safronova, seated in a train carriage among the evacuees.
Russia is also targeting southern Ukraine, where officials said shelling had killed a civilian and damaged scores of houses in Zaporozhzhia and missiles had destroyed an industrial facility in Kryviy Rih.
Moscow has blockaded ships from southern Ukraine that would normally export Ukrainian grain and sunflower oil through the Black Sea, pushing up prices globally and threatening lives.
Russia has blamed Western sanctions for the food crisis. It said on Wednesday it was ready to provide a humanitarian corridor for vessels carrying food to leave Ukraine but sanctions would need to be lifted in return.
Russian Deputy Foreign Minister Andrei Rudenko was quoted by Interfax news agency as saying Moscow was in touch with the United Nations and did not rule out "the possibility of global talks to unblock Ukraine's ports".
Ukraine's Foreign Minister Dmytro Kuleba accused Moscow of using "blackmail" tactics to secure a relaxation of sanctions.
Britain's Defense Minister Ben Wallace also rejected the Russian suggestion of such a trade-off, saying: "That grain is for starving countries."
In the latest sign of Moscow's plans to solidify its grip on territory it has seized, President Vladimir Putin signed a decree simplifying the process for residents of newly captured districts to acquire Russian citizenship and passports.
With its invasion now into its fourth month, Russia still has only limited gains to show for its worst military losses in decades, while much of Ukraine has suffered devastation as Moscow steps up artillery strikes to offset its slow progress.
The Russian parliament scrapped the upper age limit for contractual service in the military on Wednesday, highlighting the need to replace lost troops.
Western nations have imposed severe sanctions on Russia.
The United States pushed Russia closer to the brink of a historic debt default on Wednesday by not extending its license to pay bondholders. That waiver has allowed Moscow to keep up government debt payments till now.
The European Commission proposed on Wednesday to make breaking EU sanctions against Russia a crime. The EU also said it hoped to reach agreement on sanctions on Russian oil before the next meeting of EU leaders.
But Russia, for now at least, is not short of money. Oil and gas revenues stood at $28 billion in April alone thanks to high energy prices.
Putin on Wednesday ordered the government to hike old-age pensions and the minimum wage by 10%, while stating that not all economic problems were linked to what he calls Russia's "special military operation" in Ukraine.
In a speech by video link to dignitaries at a global forum in Davos, Switzerland, Zelenskiy said the conflict could only be ended with direct talks between him and Putin.
As a "first step towards talks", Russia should withdraw to lines in place before its Feb. 24 invasion, he said. Prior to the invasion, Russia held Ukraine's Crimea peninsula, while its separatist proxies occupied parts of the Donbas.
Ukraine's closest allies say they fear some Western nations might push Kyiv to give up land for peace. Estonia's prime minister said Ukraine should not be forced into compromises.
"It is much more dangerous giving in to Putin than provoking him. All these seemingly small concessions to the aggressor lead to big wars. We have done this mistake already three times: Georgia, Crimea and Donbas."