The White House has warned Ukrainian President Volodymyr Zelensky to stop criticizing President Trump and sign an agreement to hand over $500 billion of rare earth minerals and other resources as payment for U.S. wartime aid. National security adviser Mike Waltz made the threat from the White House briefing room on Thursday.

Reporter: “Zelensky publicly rejected this deal about the rare earth minerals. Where does that stand?”

Mike Waltz: “Well, we’re going to continue to have — he needs to come back to the table, and we’re going to continue to have discussions about where that deal is going.”

This comes after Trump lashed out at Zelensky, mocking him as a “dictator without elections” in an error-riddled rant on social media. Zelensky met in Kyiv Thursday with Trump’s envoy to Ukraine, Keith Kellogg, but canceled a scheduled joint press conference after the talks. The U.S. has objected to a draft of a G7 resolution calling Russia the “aggressor” in its invasion of Ukraine; separately, Reuters reports the U.S. is refusing to co-sponsor a U.N. motion backing Ukraine on the third anniversary of Russia’s invasion.