U.S. President Donald Trump says he has called Russian President Vladimir Putin and begun to arrange a meeting between Putin and Ukrainian President Volodymyr Zelenskyy, a critical step toward bringing a possible end to Russia's war on Ukraine.

President Trump and European leaders met for a one-of-a-kind summit at the White House on Monday to push toward a peace deal between Russia and Ukraine. But by the end of a marathon day of meetings, details on what such an agreement might entail remained elusive.