President Trump’s harsh words in recent days about President Vladimir V. Putin marked a sharp break from the strikingly positive posture he has taken for years toward the Russian leader.

During the 2016 presidential campaign, Mr. Trump repeatedly praised Mr. Putin and predicted the two men would forge a productive relationship. When Russia was preparing to invade Ukraine in 2022, Mr. Trump called Mr. Putin a “genius” for moving to seize large swaths of territory — applauding what he viewed as hard-line negotiation tactics.

“How smart is that? And he’s going to go in and be a peacekeeper,” Mr. Trump said, adding: “Here’s a guy who’s very savvy. I know him very well.”

As Mr. Putin’s army slaughtered civilians in a Ukrainian suburb and abducted Ukrainian children to Russia, Mr. Trump called such actions “terrible,” but stressed that he “got along with him really well.” Mr. Putin responded with his own compliments, saying that he couldn’t “help but feel happy about” Mr. Trump’s continued support for a negotiated peace favorable to Russia.

Many of Mr. Trump’s comments about Mr. Putin have reflected his anger about the U.S. investigations into Russian interference in the 2016 election that dominated his first term.

“Let me tell you, Putin went through a hell of a lot with me,” he said in February, seated next to President Volodymyr Zelensky of Ukraine in the Oval Office.