>>...it is impossible to negotiate with Valdimir Putin because he cannot be trusted

Agreed 110% on this. It doesn't so much make negotiation impossible as it makes it pointless - why give up something in good faith when the other side most probably has no intention of honoring any agreement?

On to your more general argument, which seems to be that NATO should force Ukraine to the negotiating table even when it's against their interest. Ukraine being a sovereign nation to the side, you are ignoring what happens *after* and agreement is made. If you want to be persuasive, maybe show why Putin would stop *permanently* at any negotiated border short of the geographic barriers that separate Europe from the heartlands of Russia? I expect you can't - but surprise me.

Without a reliably permanent end to Russian expansion Ukraine is defending the eastern parts of NATO from Russian aggression, so it is clearly not in NATO's interest to force Ukraine to negotiate.

To quote an old saw: "Nations don't have friends; they have interests".