President Donald Trump said Friday that he was unsure if he’d be able to end Russia’s war against Ukraine, a far cry from his promise to swiftly put a stop to the conflict that he made on the campaign trail.

President Trump said on Thursday that a phone call with President Vladimir V. Putin of Russia had not resulted in any movement toward ending the war in Ukraine, adding that he was “not happy” with the conflict grinding on. “I didn’t make any progress with him at all,” Mr. Trump told reporters.

The call with Vladimir Putin came as Ukrainian President Volodymyr Zelensky said publicly he wants to discuss weapons supplies with President Trump.