Negotiation doesn’t mean that your adversary will always do what they say, and it’s not a matter of trust. What negotiation is about is finding situations where both parties are most likely to avoid open conflict because it would be more costly for them than the alternative compromise.

Negotiating with Russia does not guarantee that you'll get what you want. Yet, negotiation is preferable to all out war because there is a chance of precluding it. One has to be a special kind of imbecile in order to not understand this.

And now Ukraine and Russia made a deal, which Russia immediately broke (they admitted it the bombing today). And this is the diplomacy which is needed in your opinion?

Read the rest of my reply where I explain in detail why Russia is now in the position to break the deal, and why negotiating BEFORE the war started had a much better chance of avoiding the current situation.

Please explain how are you going to go forward with diplomacy if the invader here is not to be trusted in even deals and negotiations like this? And you honestly expect after all this any military negotations are going to work any better?

Again, as I explained in my reply which you evidently did not read, we're past the point where any meaningful negotiation is possible. Russia will now dictate its terms to Ukraine and to the west.