The head of the European Commission, Ursula von der Leyen, stated the need to provide Ukraine with security guarantees similar to Article 5 of the NATO charter. She said this during a meeting with the US President and EU leaders in Washington, as reported by UNN.
"We are working on security guarantees. Article 5 (of NATO - ed.) speaks of security guarantees," she said.
Addition
US President Donald Trump stated that Ukraine would not be in NATO, but would have "good security guarantees" and "very good protection."
For reference
Article Five of the NATO Charter is the fundamental principle of the Alliance's collective defense. According to it, an attack on one or more NATO members will be considered an attack on all.