Andriy Yermak, the head of Ukrainian President Volodymyr Zelensky’s office, called Russian President Vladimir Putin the “ultimate evil” following the death of opposition leader Alexei Navalny.

“[P]utin is the ultimate evil who is afraid of any competition. The lives of [R]ussians are nothing to him,” Yermak wrote Friday on X, the platform formerly known as Twitter

“Everyone who calls for negotiations must realize that he cannot be trusted. The only language he understands is force,” he added.

The Russian prison service reported Friday that Navalny had died after he began feeling unwell while on a walk and losing consciousness. U.S. officials and democratic leaders around the world have blamed Putin for Navalny’s death.

“Obviously he was killed by Putin, like thousands of others who have been tormented, tortured because of this one person,” Zelensky said Friday, according to a translation.

“Putin doesn’t care who dies, as long as he retains his position. And that is why he must not keep anything. Putin must lose everything. He must not retain anything and must be held accountable for what he has done,” Zelensky continued.

The comments come as the House struggles to pass President Biden’s supplemental aid package that would include funding for Ukraine.

National security officials have stressed the importance of delivering more military assistance to Ukraine, as the country approaches the two-year mark since Russia first officially launched its invasion of Ukraine.

Supporters of Ukraine aid have pointed to Navalny’s death as demonstrative of the importance of aiding Ukrainians in their efforts to defeat Putin.

“Make no mistake,” Biden said at a press conference Friday. “Putin is responsible for Navalny’s death. Putin is responsible. What has happened to Navalny is yet more proof of Putin’s brutality. No one should be fooled.”

The president, at the press conference, called on House Republicans to pass billions of dollars in aid for Ukraine, saying Navalny’s death “reminds us of the stakes of this moment.”

“We have to provide the funding so Ukraine can keep defending itself against Putin’s vicious onslaughts and war crimes,” Biden said.

“History is watching the House of Representatives,” Biden added. “The failure to support Ukraine at this critical moment will never be forgotten.”