A month since Russia launched its shock invasion, Ukraine's leader pleaded Thursday for NATO to "save" his shattered country with unrestricted military aid, so its armed forces could transform their dogged defense into attack.
While Kyiv and Western intelligence report battlefield gains against the Russians, the vast scale of civilian suffering was made stark as the UN said more than half of all Ukraine's children have been driven from their homes.
After urging global street protests to denounce the war, President Volodymyr Zelensky told NATO leaders that Russia had unleashed phosphorus bombs on Ukraine along with indiscriminate shelling of civilians.
"A month of heroic resistance. A month of the darkest suffering," he said in a video speech to U.S. President Joe Biden and other alliance leaders, at the first of three Brussels summits that are expected to tighten the sanctions screws on Russia.
"To save people and our cities, Ukraine needs military assistance without restrictions," Zelensky said. "In the same way that Russia is using its full arsenal without restrictions against us."
At least four people including two children were killed in Russian strikes in eastern Ukraine, Lugansk regional governor Sergiy Gayday said, accusing Russian forces of using phosphorus bombs in one village.
Britain's ITV network showed footage of the incendiary weapons — which cause horrific burns — dropping in a white haze overnight on Irpil near Kyiv.
"(Russian President) Vladimir Putin has already crossed the red line into barbarism," British Prime Minister Boris Johnson said in Brussels.
Zelensky wants NATO to help Ukraine go on the offensive with more advanced fighter jets, missile defense systems, tanks, armored vehicles and anti-ship missiles.
Ahead of the summits of NATO, the G7 and the European Union, Ukraine's leader said: "At these three summits we will see: Who is a friend, who is a partner, and who betrayed us for money.
"Life can be defended only when united."
Zelensky's appeal came one month to the day after Russian armored vehicles rolled over the border, igniting a conflict that is feared to have killed thousands of Ukrainian civilians, along with thousands more soldiers on both sides.
More than 10 million Ukrainians have fled their homes, as cities have faced sustained Russian bombardment from land, sea and air.
The month of war has displaced 4.3 million children — more than half of Ukraine's estimated child population of 7.5 million, according to the UN children's agency Unicef.
"This is a grim milestone that could have lasting consequences for generations to come," Unicef chief Catherine Russell said.
UN figures show that more than 3.6 million Ukrainians including 1.8 million children have fled abroad, and more are now displaced inside Ukraine after harrowing journeys out of cities like Mariupol.
In the besieged southern port, Zelensky says nearly 100,000 people are trapped without food, water or power and enduring fierce shelling by Russian forces.
In Zhytomyr, a garrison town west of Kyiv, a Russian strike flattened the school where Vasiliy Kravchuk's six-year-old son was meant to start at next year.
"It's hard, it's very hard," sobbed the 37-year-old, who works for a tourism organization which is now bereft of tourists.
"Every day it's 20, 30 times we go to the basement (to shelter). It's difficult because my wife is pregnant, I have a little son," says Kravchuk, wearing a bright pink hoodie and rubbing his eyes.
Experts say Russia's once-vaunted military has been bogged down by dogged resistance, logistical problems and low morale and has turned to long-range bombardment in the hope of breaking Ukrainian resolve.
In the back-to-back Brussels summits, Biden and other leaders are expected to bring pledges of more lethal weapons to Ukraine and more punishing sanctions for Russia's tottering economy.
Britain's Johnson said that as well as increasing military support to Ukraine, "we've got to go further" economically — including by preventing Russia using its gold reserves.
"The more we do that now, the more pressure we apply now, particularly on things like gold... I believe the more we can shorten the war, shorten the slaughter in Ukraine," he said.
NATO chief Jens Stoltenberg said the summit will see leaders agree to "major increases of forces" on the alliance's eastern borders, including four new battle groups in Bulgaria, Hungary, Romania and Slovakia.
Putin had made a "big mistake," Stoltenberg said.
"He has underestimated the strength of the Ukrainian people, the bravery of the Ukrainian people and their armed forces."
Ukraine's navy said it had struck a Russian naval transport vessel docked in the Azov Sea near Mariupol.
Amateur footage showed plumes of black smoke billowing from a large grey vessel docked next to cranes, after what the Ukraine navy said was the strike, which AFP could not independently confirm.
Putin's regime has introduced draconian censorship laws to prevent independently verified news about what it calls a "special military operation."
British military intelligence said Ukraine had "probably retaken Makariv and Moschun" near Kyiv and "there is a realistic possibility that Ukrainian forces are now able to encircle Russian units in Bucha and Irpin."
What is clear is that Ukrainian civilians continue to bear the brunt of the war.
"There's going to have to be a further, massive scaling up of assistance within Ukraine in the coming weeks," said Michael Ryan, emergencies director for the World Health Organization.
"I have never, myself, seen such complex needs, and so quickly in a crisis that has developed so fast," he said. "We have reached maybe, for once, an appropriate level of horror at what's happening in Ukraine."
Moscow confirmed that Anatoly Chubais — a former Kremlin chief of staff who oversaw liberal economic reforms in the 1990s — had quit his post as a Putin advisor. He has reportedly fled the country in protest at the war.
Russia still has a vital friend in China, which dismissed suggestions that Moscow should be expelled from the G20 group of countries.
China must meet its "responsibilities" over Ukraine, a U.S. official said in Brussels, after Stoltenberg accused it of "spreading blatant lies" on Russia's behalf.