Special U.S. envoy Steve Witkoff says Russian leader Vladimir Putin agreed to allow the U.S. and Europe to offer Ukraine a security guarantee resembling NATO's collective defense mandate.

U.S. President Donald Trump could offer NATO-like protection of Ukraine, and Russia is open to the idea, one of his top foreign policy officials said on Sunday ahead of a meeting with Ukraine and European leaders to hammer out details of possible security guarantees for Kyiv.

After the Trump-Putin summit, European leaders said they would accompany President Volodymyr Zelensky of Ukraine to the White House on Monday.