In my view, it's more naïve to write Putin off as a madman and continue having 1000s killed and maimed every day, because you don't believe Putin capable of upholding a treaty.

Make the peace deal, sign the treaty and then if they break it, at least we'll know that we've exhausted all our options.

And yes, Ukraine will have to make some concessions - this is bigger than any one country anymore, this is for world peace.