Ukrainian President Volodymyr Zelensky accused Russia on Thursday of using phosphorus bombs, which are restricted but not entirely banned under international conventions.
“This morning we had phosphorus bombs from Russia, people were killed, children were killed,” Zelensky told NATO leaders meeting in Brussels for an emergency summit regarding the war, NBC News reported.
White phosphorus ignites on contact with air. It is typically used in wars to mark enemy targets or create a smokescreen to hire troop movements, but can also start fires and kill or maim anyone who comes in contact with it.
Among the points of discussion at the Brussels meeting is determining what actions Russia could take that would require NATO to get more directly involved in the war, The Wall Street Journal reported.
NATO members have so far supplied military and humanitarian aid to Ukraine, but have refused sending troops or implement a no fly zone.
The Pentagon said Wednesday it wasn’t able to confirm the use of phosphorus bombs in Ukraine, according to NBC News.
The accusation by Zelensky comes a day after President Biden again warned of Russia using chemical weapons.
“I think it’s a real threat,” Biden said when asked about Russia using chemical weapons before he left for Brussels to join the discussions.
Phosphorous is not considered a chemical weapon under international law.
The U.S. accused Russia of war crimes on Wednesday after Russia has escalated shelling of civilian targets including hospitals, schools and bomb shelters.
The U.N. has confirmed more than 1,000 civilians have been killed, although they say the true total is likely much higher.