For the first time, US President Joe Biden accused Vladimir Putin’s forces of genocide in Ukraine, as Russia was stepping up its campaign to retake the damaged port city of Mariupol. Biden’s accusation came as Moscow was suspected of preparing a massive attack throughout eastern Ukraine, which Washington warned may include chemical weapons.

“Yes, I called it genocide. We will let the lawyers decide whether it qualifies, but it certainly seems that way to me. It’s become very obvious that Putin is just trying to eliminate the idea of even being able to be a Ukrainian,” Biden said. Ukrainian President Volodymyr Zelensky responded to Biden on Twitter, “True words of a true leader.”

Biden had earlier described Putin as a “war criminal” due to the discovery of hundreds of civilians reportedly killed in Bucha, which sparked global hatred toward Russia. But he had stopped using the term “genocide” to stay in line with US protocol because of its strictly legal definition and the serious implication the accusation carries.