Sri Lanka, Feb. 20 -- U.S. President Donald Trump denounced Ukrainian President Volodymyr Zelenskiy as a "dictator" on Wednesday and warned he had to move quickly to secure peace or risk losing his country, deepening a feud between the two leaders that has alarmed European officials.

The extraordinary attacks - a day after Trump claimed Ukraine was to blame for Russia's 2022 invasion - heightened concerns among U.S. allies in Europe that Trump's approach to ending the Russia-Ukraine conflict could benefit Moscow.

Less than a month into his presidency, Trump has upended U.S. policy on the war, ending a campaign to isolate Russia with a Trump-Putin phone call and talks between senior U.S. and Russian officials that have sidelined Ukraine....