The feud between President Trump and Volodymyr Zelensky has been fueled by the Ukrainian president’s refusal to sign a deal handing hundreds of billions of dollars in minerals to the U.S.

Donald Trump isn’t the only president who knows a bad deal when he sees one. Volodymyr Zelensky’s refusal to sign away nearly half of his country’s rare earth minerals for very few future guarantees is one of many reasons why Trump has been driven into a rage at his counterpart in Kyiv.