United States President Joe Biden has branded Vladimir Putin a "war criminal" as the Russian leader's onslaught in Ukraine claimed more civilian lives, and a theatre where "hundreds" were sheltering was destroyed by bombing.
Mr Biden's rebuke — his sharpest yet — came after Ukraine's leader Volodymyr Zelenskyy made a searing appeal for help to the US Congress and the president himself, who responded by pledging $1 billion ($1.37 billion) in new weapons to fight Russia's invading army.
Officials in the port city of Mariupol were struggling to count the dead at the Drama Theatre, where thick smoke rose from the rubble of the building that had the word "children" painted in large Russian letters on the ground outside.
It was the latest in a litany of assaults on civilians across Ukraine since Mr Putin invaded on 24 February that has included homes, hospitals, ambulances and food queues.
"I think he is a war criminal," Mr Biden told reporters of his Russian counterpart, the first time he has used the phrase.
Mr Biden's spokesperson added that he had spoken "from his heart" — but the Kremlin quickly punched back, calling the comment "unacceptable and unforgivable on the part of the head of a state, whose bombs have killed hundreds of thousands of people around the world."
So far the destruction that has marked other cities has been halted outside Kyiv.
But dull booms echoed across the capital's deserted streets on Wednesday, with only an occasional vehicle passing through sandbagged checkpoints, and very few permits granted to break its latest curfew.
Kyiv has been emptied of around half of its 3.5 million people.
"It's worrying, of course. It's war after all. But we try to stay calm, we won't allow panic," said Eduard Demenchuk, a private-security employee in his 50s, who was among those who have stayed.
"If need be, we will take arms and will stand to defend the city," he told news agency AFP by telephone, after stocking up on groceries for the curfew.
Damaged vehicles and buildings in Kharkiv city centre in Ukraine, on Wednesday, 16 March, 2022. Source: AAP, AP / Pavel Dorogoy
'Destruction of hope'
The attack on the theatre in Mariupol is the latest atrocity in the southern city, which has been besieged for weeks, with more than 2,000 people killed so far.
Mariupol city authorities said Russia "purposefully destroyed" the theatre, though Moscow blamed Ukrainian forces for the blast.
Efforts to establish the number of casualties were hampered by nearby shelling.
"It is impossible to find words to describe the level of cynicism and cruelty," the city authorities said in a statement.
Also on Wednesday, at least 15 civilians were killed in the northern city of Chernihiv.
Ten of them died while queueing to collect bread. Another five, including three children, were killed when Russian forces shelled a residential building.
As the civilian toll climbed, the World Health Organisation warned that Ukraine's health system was "teetering on the brink."
"This is about the destruction of hope ... This is the most basic of human rights and it has been directly denied," WHO official Michael Ryan said in Geneva.
French prosecutors meanwhile opened a war crime probe into the death of Franco-Irish Fox News cameraman Pierre Zakrzewski, shot near Kyiv on Monday.
The conflict has already sent more than three million Ukrainians fleeing across the border, many of them women and children.
Ukraine's parliament, citing the country's prosecutor general, said on the messaging app Telegram that 103 children have been killed since the invasion began.
'Leader of peace'
In a virtual address to Congress, Mr Zelenskyy invoked Pearl Harbor, the 9/11 attacks and Martin Luther King Jr as he showed lawmakers a video of the wrenching effect of three weeks of Russian attacks.
Mr Zelenskyy, bearded and dressed in military green, demanded Washington and its NATO allies impose a no-fly zone, so that "Russia would not be able to terrorise our free cities."
Switching to English, Mr Zelenskyy addressed Mr Biden directly, saying: "I wish you to be the leader of the world. Being the leader of the world means to be the leader of peace."
Ukrainian President Volodymyr Zelenskyy addressed the US Congress via videolink on 16 March, 2022. Source: Getty, AFP / J. Scott Applewhite
On Wednesday Mr Biden announced the US's "unprecedented" latest package of new weapons aid to Ukraine added up to $1 billion ($1.37 billion) and that the US would help Ukraine acquire longer-range anti-aircraft weapons.
Mr Zelenskyy's speech received standing ovations from lawmakers.
Mr Putin, however, at a televised government meeting also reached back to history as he denounced the West's "pogroms" against Russia and its sanctions "blitzkrieg."
He insisted the invasion was "developing successfully" adding "we will not allow Ukraine to serve as a springboard for aggressive actions against Russia."
Damaged residential buildings and shops along a street that was hit by a Russian shelling in Kyiv, Ukraine, on 15 March, 2022. Source: AAP / SOPA Images/Sipa USA
Russian opposition quashed
Western sanctions against Mr Putin's regime have pushed Russia close to a default on its foreign debts.
Russia was due on Wednesday to pay $117 million ($161 million) on two dollar-denominated bonds — the first interest payment that has fallen due since it was largely shut out of the Western financial system.
The Kremlin has sought to suppress domestic opposition to the war, blocking access to at least 15 Russian and foreign-based media including the BBC and investigation website Bellingcat.
In his speech Mr Putin claimed Western leaders gave him "no option to resolve the process in a peaceful way", and Kyiv and Moscow remained far apart at another round of sputtering talks Wednesday.
Mr Peskov said a "compromise" outcome would centre on Ukraine becoming a neutral state comparable to Sweden and Austria.
A destroyed Russian army multiple rocket launcher on the outskirts of Kharkiv on 16 March, 2022. Source: Getty, AFP / Sergey Bobok
But Mr Zelenskyy's office gave the idea short shrift.
There was one glimmer of hope that talks might yet bear fruit, as the United States and Russia made their first high-level contact since the invasion began.
And many Ukrainians themselves remained defiant.
Retired tennis player Alexandr Dolgopolov went home to Kyiv to take up arms and defend his native city.
"Used to be rackets and strings, now this," the 33-year-old wrote on Instagram alongside a photo of a rifle, helmet and flak jacket.
The mayor of Ukraine's southern city of Melitopol was released days after Kyiv said he was abducted by Russian forces.
"Thank you for not abandoning me." Ivan Fedorov told Mr Zelenskyy, according to video of their phone call posted on Telegram.
"I will need one or two days to recover and then I will be at your disposal to contribute to our victory."
