President-Elect Donald Trump delivered a stern message to Vladimir Putin during their first post-election phone call, warning the Russian tyrant against escalating the war in Ukraine.

Although the details of the call are not clear, a former U.S. official familiar with the conversation tells the Washington Post that Trump wants to prevent any worsening of the conflict before taking office in January. During the call, the former president also emphasized America’s substantial military presence in Europe as a deterrent and expressed interest in future talks aimed at resolving the conflict.

The former president’s intervention marks a significant shift from current U.S. policy, as President Joe Biden has not spoken with Putin since 2022. Ukrainian officials were also reportedly informed of the Putin call and did not object to the conversation.

“President Trump won a historic election decisively, and leaders from around the world know America will return to prominence on the world stage,” said Trump’s communications director Steven Cheung. “That is why leaders have begun the process of developing stronger relationships with the 45th and 47th President because he represents global peace and stability.”

Speaking from Moscow on Sunday, Kremlin spokesman Dmitry Peskov suggested US-Russia relations were heading in a positive direction.

“Trump talked during his campaign about how he sees everything through deals, that he can make a deal that will lead everyone to peace,” he said. “At least he talks about peace, not about confrontation and the desire to inflict a strategic defeat on Russia.”

While Trump has consistently claimed he could end the war in Ukraine, questions remain about his specific approach. His campaign’s messaging drew attention when campaign official Bryan Lanza suggested Ukraine might need to cede territory, declaring “Crimea is gone.” However, Trump’s team quickly distanced themselves from these comments, emphasizing that Lanza does not speak for the president-elect.