WASHINGTON — President Trump told Ukrainian President Volodymyr Zelensky that he was “gambling with World War III” during a fiery Oval Office exchange Friday — before canceling a press conference and declaring that the wartime leader was “not ready for peace.” The high-stakes visit — initially expected to include the signing of a framework deal giving the US a stake in Ukraine’s rare-earth elements — went off the rails when Zelensky seemed to condescend Vice President JD Vance.“What kind of diplomacy, JD, you are [sic] speaking about?” Zelensky asked in a critical tone of voice after a relatively cordial first...