NATO Secretary General Mark Rutte said on Thursday that it was important that Russian President Vladimir Putin understood that the West was "united" as peace talks to end its war with Ukraine begin.

"I don't know what is exactly on President Putin's mind, of course," Rutte told reporters after talks with the alliance's defense ministers. "He is a strong negotiator, he is very unpredictable, but in the end if we want to get a peace deal we need him there."

Rutte added that Ukraine would be involved in any way whatsoever in any peace deal.