There's no point in getting people to negotiate if there's no way to ensure they'll follow what has been agreed upon after leaving the table.
Negotiation is about finding a solution to a problem that leaves all parties better off if they follow the solution than if they don't. It is not always easy and sometimes coercion, in the form of sactions within EU and UN, is used to make one party realize what is best for them - but this also tends to work out not very well.
Not forcing people to do what you want is often a more succesful way of getting what you need.