The objective of this thesis is to analyze the changes in Israeli security policy. The thesis consists of four main parts. In the first part, the factors influencing the formation of Israeli security policy such as history, religion, ideology and threat perceptions are examined. Israeli military doctrine and its offensive, defensive and deterrence strategies are identified as the most important subcomponents of the security policy. The following part analyzes the changes and continuities in Israeli threat perceptions and the implementation of the military doctrine during and after the six main wars of the War of Independence, the war against Egypt in 1956, the Six Day War, the War of Attrition, the Yom Kippur War and the War in Lebanon in 1982. In the third part, the changes in Israeli security policy during 1990s are scrutinized. With the peace process, Israel&rsquo / s existential threat perception decreased but new threat perceptions of terrorism and conventional and nuclear military buildup in the region emerged / therefore security was redefined by the Israeli political and military decision-makers. In the last part the impact of the collapse of peace process and Sharon&rsquo / s coming to power on Israeli security policy is analyzed. Sharon&rsquo / s period can be defined by offensive security strategies aiming at preventing terror which has been the top security problem since the Al Aqsa Intifada. As a result, this thesis argues that Israeli security policy did not indicate significant changes until 1990s, however during 1990s Israeli security situation and security policy changed as a response to the regional and international developments. Post-2000 period witnessed changes as well with Sharon&rsquo / s returning to offensive strategies.