Until there is some semblance of detente in the Middle East Israel will never negotiate with anyone in good faith. This is why Israel is so afraid of an Iranian nuclear weapon, not that Iran would launch any kind of suicidal preemptive strike. Hopefully the delay in fulfilling this contract has a given the Russians time to modify the system to insure that it cannot be defeated the way the old systems in Syria were. As a matter of fact these same defensive systems should be sold to Syria and Lebanon if they can afford them. As long as Israel feels it has carte blanche to operate in any way it sees fit then there is no incentive to enter into a comprehensive peace agreement and we will just have more of the same in the Levant.
Iraqi police fire tear gas as thousands of protests burst into Green Zone, storm Parliament (AP)
from the article: Russia to supply Iran with S-300 defense systems