The Kremlin said on Wednesday that a Russian delegation was ready to continue peace talks with Ukraine as Moscow's invasion of the pro-Western country entered its seventh day.
“Our delegation will be ready to continue talks,” Kremlin spokesman Dmitry Peskov said, adding that Moscow's delegation expected the talks to resume on Wednesday evening.
He said that President Vladimir Putin's aide Vladimir Medinsky remained Russia's top negotiator on Ukraine but did not say where the next round of talks would take place.
A first round of talks between Russian and Ukrainian delegations took place on the Ukrainian-Belarusian border, but brought no results.
Russian troops land in Ukraine's second-biggest city Kharkiv
Meanwhile, Russian forces landed in Ukraine's second-biggest city and triggered immediate clashes in the streets of Kharkiv, the military said, following Moscow's relentless air assault across the ex-Soviet state.
The airborne operation came as US President Joe Biden branded Vladimir Putin a “dictator”, warning the sanction campaign to cripple Russia's economy would escalate and its oligarchs were being targeted.
In Biden's first State of the Union address, he hailed the resolve of the Western alliance and voiced solidarity with Ukraine as lawmakers in the US Congress gave a standing ovation to the Ukrainian people.
“A Russian dictator, invading a foreign country, has costs around the world,” Biden told lawmakers in his annual State of the Union address, promising “robust action to make sure the pain of our sanctions is targeted at Russia's economy”.
But as he spoke a Russian escalation was reported to be underway in Kharkiv, an apparent bid by Moscow to capture its first major Ukrainian city of the invasion.
Since Russian troops rolled into Ukraine last week to achieve Putin's mission of overthrowing the pro-Western government of President Volodymyr Zelensky, hundreds of civilians have been reported killed.
Russian forces have carried out a massive bombing campaign and encircled urban centres, but Ukraine insists no major city has yet been overtaken.
“Russian airborne troops landed in Kharkiv ... and attacked a local hospital,” the Ukrainian army said in a statement on messaging app Telegram.
“There is an ongoing fight between the invaders and the Ukrainians.”
Russia hit a residential building in the city on Tuesday killing eight people, drawing comparisons to the massacres of civilians in Sarajevo in the 1990s and condemnation for what Zelensky called a “war crime”.
A fire broke out on Wednesday in the barracks of a flight school in Kharkiv following an airstrike, according to Anton Gerashchenko, adviser to the Ukrainian Interior Minister.
“Practically there are no areas left in Kharkiv where an artillery shell has not yet hit,” he was quoted as saying in a statement on Telegram.
Kharkiv, a largely Russian-speaking city near the Russian border, has a population of around 1.4 million.
Russian military says has control of Kherson
The Russian army claimed on Wednesday it had taken control of the southern Ukrainian city of Kherson.
“The Russian divisions of the armed forces have taken the regional centre of Kherson under full control,” defence ministry spokesman Igor Konashenkov said in televised remarks.
He claimed that public services and transport were operating as usual.
“The city is not experiencing shortages of food and essential goods,” he added.
He said talks were under way between the Russian army and local authorities on maintaining order, protecting the population and keeping public services functioning.
Kherson's mayor Igor Kolykhaiev said in a post on Facebook: “We are still Ukraine. Still firm.”
Apparently contradicting the Russian army's claims, he said he needed to find a way to “collect the (bodies of the) dead” and “restore electricity, gas, water and heating where they are damaged”.
“But I warn you right away: to complete these tasks today means to perform a miracle,” he added.
'Putin was wrong'
Biden, who had earlier spoken with Zelensky on the phone, announced new measures against Russia and its wealthy elite with a new task force to go after the “crimes” of Russian oligarchs.
“We are coming for your ill-begotten gains,” he said, prompting the rare sight of members of both parties standing to applaud.
“And tonight I am announcing that we will join our allies in closing off American air space to all Russian flights — further isolating Russia and adding an additional squeeze on their economy.”
The US leader said Putin's aggression was “premeditated and totally unprovoked” — but hailed the resolve of the Western alliance in responding with brutal sanctions.
“(Putin) thought he could divide us here at home,” Biden said. “But Putin was wrong. We are ready.”
He repeated his commitment that no American troops would be sent to Ukraine to confront the invading forces.
Read: Condemnations, warnings and sanctions: What global leaders are saying as Russia-Ukraine conflict intensifies
A lack of will to send foreign troops into battle has given Russia space to press on with its assault on Ukrainian cities.
A strike on the main TV tower in Kyiv killed five people on Tuesday and knocked out some state broadcasting, Ukrainian officials said, but left the structure intact.
Fresh explosions were heard late on Tuesday in Kyiv and Bila Tserkva, 80 kilometres to the south, according to local media.
News outlets also reported Russian missiles damaging residential buildings and a hospital in Zhytomyr, citing the major transport hub's mayor Sergei Sukhomline.
The International Criminal Court has opened a war crimes investigation against Russia.
Ukraine says more than 350 civilians, including 14 children, have been killed in the conflict.
Belarus attack fears
The Ukrainian Ministry of Defence also said overnight that it feared an attack from Belarus over its northern border.
“Belarusian troops have been put on high alert and are concentrated in areas closest to the border with Ukraine,” the ministry said on Tuesday in a statement on Facebook.
Ukrainian intelligence noted “significant activity” of aircraft in the border area, it said.
Belarusian President Alexander Lukashenko said on Tuesday he had ordered more troops to the south of the country, the Belta news agency reported.
But forces of Belarus, a close ally of Russia, would not be taking part in the attack on Ukraine, he added.
In southern Ukraine, the city of Mariupol on the Azov Sea was left without electricity after Russian bombardment.
In a key victory for Moscow, Russia's defence ministry said its troops had linked up with pro-Moscow rebel forces from eastern Ukraine along the Azov Sea coast.
Companies exit Russia
Russia has defied international bans, boycotts and sanctions to press ahead with an offensive it says is aimed at defending Ukraine's Russian speakers and toppling the leadership.
In response, more Western companies have withdrawn from projects in Russia, deepening the economic toll on Moscow that saw the ruble collapse this week.
Apple, ExxonMobil and Boeing announced on Tuesday in rapid succession steps to withdraw or freeze business in Russia.
The moves followed earlier announcements by Disney, Ford and Mastercard among others.
The invasion has sent global markets into a spiral, with crude surging past $110 a barrel on Wednesday and equities sinking.
On top of sanctions, Germany has promised arms for Ukraine, while the EU said, in a first, that it will buy and supply arms to the country.
Zelensky has reiterated an urgent appeal for Ukraine to be admitted to the European Union.
More than 660,000 people have fled abroad, the UN refugee agency said, and as battles rage for control of major cities many more are expected to follow.
Residents of capital Kyiv are crammed into makeshift bomb shelters awaiting their own fight, with a massive Russian military convoy stationed just north of the city.
Teacher Irina Butyak, 38, has spent two days in the basement of her apartment block sheltering with some 20 people.
“We have train tickets for western Ukraine for tomorrow,” she told AFP as air raid sirens blared directly overhead.
“I don't think we will make the train.”