This paper studies what situation Israel will face because of nuclear development in Iran. My approach is based on the theory of the international system applied to the regional level and we can discuss the probability of conflict in accordance with the change of balance of power. The game theoretic model of the Middle Eastern regional system leads to an implication that the Israelis recognize the threat of Iranian nuclear weapons and feel security from the alliance with the United States and Western countries. The study produces a scenario as follows:the nuclear Iran will erode Israel's military superiority and would not raise the danger of war but make Israel follow a policy of appeasement in the Palestinian issue.