Ukraine has expressed concern at the level of security guarantees against Russian aggression in a U.S. proposal. President Donald Trump has said part of a peace deal could see Kyiv barred from joining NATO. Zelensky's comments suggest that Ukraine can benefit from security guarantees outside of the alliance's mutual defense pact.

Discussions between the US, United Kingdom, Ukraine, France and Germany ended Wednesday without agreement on the terms of a potential peace deal — but with promises to keep talking.

After the Ukrainian leader criticized President Trump’s proposed peace plan, U.S. officials again threatened to walk away from negotiations.