Donald Trump has ruled out sending US troops to Ukraine to enforce a potential peace deal with Vladimir Putin, tempering a promise to provide Kyiv with security guarantees that European allies had called a significant breakthrough towards halting the Kremlin’s invasion of Ukraine.

Asked during a phone interview with Fox News whether he could assure listeners – including many members of his Maga base who support an isolationist America-first foreign policy – that the US would not put troops on the ground in Ukraine, he said: “You have my assurance, and I’m president.”

Trump did, however, say Washington may be willing to provide air support to Ukraine in order to backstop a deal, in what would still be a remarkable shift in his administration’s policy on the conflict.