Zelensky Accuses Russian Forces of Using Phosphorus Bombs in Ukraine

President Volodymyr Zelenskyy has accused Russia of using phosphorus bombs in attacks on Ukraine Thursday, killing both adults and children.

Zelenskyy made the claim during a video address to NATO members gathered for an emergency summit in Brussels. It comes a day after Ludmyla Denisova, Ukraine's Human Rights Ombudswoma, accused Russia of using white phosphorus munitions in Luhansk region. The Pentagon told NBC News it wasn't able to confirm that allegation.

White phosphorus munitions "operate in the same way as incendiary weapons" by "setting fires and causing burns" with the capability to cause fire to spread over a wide area, according to Human Rights Watch. They aren't banned under international law, but it's usage is restricted in populated areas is prohibited under Protocol III to the 1980 Convention on Conventional Weapons.

Asked Thursday about Zelensky's claim, NATO Secretary-General Jens Stoltenberg told MSNBC's Andrea Mitchell that the alliance is being cautious about "every report we see about different types of weapons used."

"But, what I can say is that have seen what the rest of the world has seen, that civilian infrastructure and civilian residential areas have been attacked again and agin in different cities and we are seeing a high number of civilian casualties," he said. "And this highlights the importance of ending this war."

Zelensky reminded NATO leaders that thousands of Ukrainians have died in the past month, 10 million people have left their homes, and urged the coalition to give “clear answers.”

“It feels like we’re in a gray area, between the West and Russia, defending our common values,” Zelenskyy said emotionally. “This is the scariest thing during a war -- not to have clear answers to requests for help.”

He pleaded with NATO to provide his embattled nation with military assistance, noting Russia is “using its entire arsenal” against the country. He specifically asked for anti-air and anti-ship weapons. And although Zelenskyy thanked Western nations for support they already have provided, his frustration was clear.

He urged NATO to provide Ukraine with “1% of all your planes, 1% of all your tanks.” “We can’t just buy those,” Zelenskyy said. “When we will have all this, it will give us, just like you, 100% security.”

This is a live update. Click here for complete coverage of the crisis in Ukraine.