The precondition may not be related to what will be discussed, or it may be used as a starting point for the discussion. "We will only start negotiations with Country X if the precondition of a cease-fire is met". In this case, a cease-fire would be a sign of faith that Country X is willing to agree to start working towards a solution to end hostilities.

Or think of it in other non political terms. A precondition to a company agreeing to interview me would be to submit a resume to them first on their web site.