Last week’s Oval Office meeting between former U.S. President Donald Trump and Ukrainian President Volodymyr Zelensky was meant to solidify a critical alliance in the face of Russia’s ongoing aggression. Instead, the Trump-Zelensky meeting laid bare the deepening divisions between the two nations, casting doubt on the future of U.S. support for Ukraine.

In a stunning political comeback that has left the world in awe, Donald Trump has been elected the 47th President of the United States,...