Polish Prime Minister Donald Tusk warned U.S. President Donald Trump’s apparent pro-Ukraine shift could actually signal American disengagement from the war with Russia.

Trump, who has long parroted Kremlin talking points about Moscow’s full-scale invasion and said Ukraine will never reclaim its pre-2014 borders, surprised allies when he suggested this week Kyiv could fight and totally defeat Russia with European backing.

The EU was quick to take credit for the about-face, with a spokesperson for the European Commission claiming Trump has been influenced by regular contact with President Ursula von der Leyen.

But Tusk had a different take on Trump’s apparent U-turn. Reading between the lines, the U.S. president was seemingly backing away from his pledge to end the conflict, the Polish leader warned Thursday.

“President Trump has stated that Ukraine could, with the support of the European Union, regain all of its territory. This surprising optimism conceals a promise of reduced U.S. involvement and a shift of responsibility for ending the war to Europe,” Tusk wrote on social media. “Truth is better than illusion.”

Trump has previously threatened to walk away from negotiations between Ukraine and Russia, and has admitted the war is proving more difficult to end than he expected — though he shocked Western allies with Tuesday night’s missive.

“I think Ukraine, with the support of the European Union, is in a position to fight and WIN all of Ukraine back in its original form,” he wrote on social media shortly after a meeting with Ukrainian President Volodymyr Zelenskyy on the sidelines of the United Nations General Assembly.

“We will continue to supply weapons to NATO for NATO to do what they want with them. Good luck to all!” he added.

His whiplash-inducing pivots on the conflict, from denouncing Russian President Vladimir Putin as “absolutely CRAZY” to embracing him at a summit in Alaska a few months later, or pausing, then restarting delivery of military aid to Ukraine, have left Kyiv and its allies anxious about where Washington really stands.