President Trump swept into office with a declaration that he could bring Europe’s deadliest war in a generation to a swift end.

But after a phone call on Monday with President Vladimir V. Putin of Russia, Mr. Trump appears prepared to step back from his role trying to end the war in Ukraine.

For many Ukrainians, the call marked the last gasp of a chaotic process that few believed had any chance of success as long as the United States refused to apply pressure on Moscow. And that means the long and devastating war will rage on with no end in sight.

Olena Boiko, 41, called Mr. Trump’s diplomatic effort to bring the conflict to a halt a “theatrical performance that has nothing to do with the reality of trenches or bomb shelters.”

Ms. Boiko, who fled from a village near the border to Sumy, a city in northeastern Ukraine which itself is under relentless bombardment, said she and her family had suffered immense losses during the war and desperately wanted it to end.

“My daughters and I have lost the most precious things to this war — my husband, their father, and my childhood home, which was destroyed down to its foundation,” Ms. Boiko said.