Russian forces left a trail of destruction Thursday, seeking to push deeper into the eastern Donbas region as President Vladimir Putin said his military campaign was still ramping up.
Diplomatic tensions meanwhile mounted between Ankara and Kyiv, with Ukraine accusing Turkey of ignoring calls to seize Ukrainian grain being transported by a Russian ship.
A Russian air strike in the eastern Ukrainian industrial city of Kramatorsk left at least one dead and several others wounded earlier in the day, as Russian troops fight for full control of the surrounding Donbas.
The explosion left a gaping crater next to a hotel and residential buildings and several cars were on fire, AFP journalists said, as emergency services arrived on the scene.
It came ahead of a speech by Putin to lawmakers in which he said "everyone should know that we have not started in earnest yet."
He also sounded a note of menace towards the West, telling the alliance that has coalesced against his invasion of Ukraine that if they wanted to defeat Russia on the battlefield "let them try."
The head of Ukraine's battled-scarred Donetsk region, Pavlo Kyrylenko, announced before the strike on Kramatorsk that Russian bombardments had killed at least seven people over the past 24 hours.
The fatalities came after Ukrainian officials again called for civilians in the region to flee, as Russian forces turn their sights on the city of Sloviansk.
Battle for cities
Russian troops captured cities in the Luhansk region after long battles, consolidating their hold in the east after failing at the start of the February invasion to take the capital Kyiv and Ukraine's second-largest city Kharkiv.
Despite the raging conflict, Kyiv took time to hail outgoing U.K. Prime Minister Boris Johnson, one of Ukraine's keenest allies throughout the war.
Johnson said that even though he was leaving office, Britain would continue supporting Ukraine for "as long as it takes."
"We all welcome this news with sadness. Not only me, but also all of Ukrainian society," President Volodymyr Zelensky said, after Johnson resigned as leader of Britain's Conservative party, paving the way for the selection of a new prime minister.
"We don't doubt that Great Britain's support will continue, but your personal leadership and your charisma made it special," he said.
In the diplomatic clash between Ukraine and Turkey, Kyiv says that a 7,000-ton vessel set off from Ukraine's Russian-occupied port of Berdyansk after picking up wheat.
The marinetraffic.com website on Thursday showed the vessel moving away from Turkey's Black Sea port of Karasu before apparently switching off its transponder and disappearing from view.
Ukraine said it was "deeply disappointed" that Turkey had not seized the ship.
Control over Snake Island
Zelensky in his evening address again called for more arms from international allies.
"The bigger defense support to Ukraine will be now, the quicker the war will end with our victory and the lesser will be losses of all countries in the world," he said.
Ukraine this week also said it had regained control of Snake Island in the Black Sea, raising its flag there following the withdrawal of Russian forces.
"I want to thank for the final stage of the fight for Snake Island. Our national flag was erected there. This operations lasted for two months," Zelensky said.
"Let now every Russian captain of a ship or a plane see the Ukrainian flag at Zmeiny and know that our country cannot be broken."
Russia said it pulled back from the symbolic island in a gesture of "good will", but has since continued targeting positions there.
The Russian defence ministry said it had carried out "precision" missile strikes on the island early Thursday, killing Ukrainian soldiers.
Finland meanwhile passed legislation to build stronger fences on its border with Russia, as the country seeks to join NATO following the invasion.
Finland reversed decades of military non-alignment by seeking membership in the military alliance in May, formally starting the process to join this week.