After his three-hour meeting with Russia’s president, Vladimir V. Putin, in Alaska more than five weeks ago, he insisted that Mr. Zelensky would have to face reality and make a deal, giving up territory to its larger and stronger neighbor. Mr. Trump provided no rationale for his stunning turnaround, though several European officials suspected that by distancing himself from the war, the president was washing his hands of a conflict that he once promised to solve in days or weeks. In his eight months in office, Mr. Trump has ricocheted from one position to another on Ukraine. In February, he slammed Mr. Zelensky for insisting on American aid, yelling at him in the Oval Office, “You don’t have the cards.” In the spring, he cultivated Mr. Putin, exempting him from tariffs. This summer, he rolled out a red carpet for him in Alaska.