In this thesis it is argued that geopolitical discourse matters in shaping the practices of foreign policy. The perspective of Critical Geopolitics approach is adopted as the theoretical framework and in conformity with this framework; this study focuses on the geopolitical discourse of the political elites. With reference to the geopolitical discourses of the political elites in Israel and Turkey, it is discussed that geopolitical discourse makes certain foreign policy options possible while marginalizing some others. Firstly, the main components of the geopolitical discourses in those countries, which are ‘exceptionalism’, ‘Jewishness’, ‘security’ in Israel and ‘geographical determinism’ and ‘ Westernness/Europeanness’ in Turkey’, are identified. Then, the case of Oslo Peace Accords and the case of Turkey-EU relations are used in order to illustrate how different framings of these components matter in terms of foreign policy practices.