When any person or group feels offended and attacked, they tend to feel "defensive". Since countries are made up of people, the same "feeling" can occur for the majority of people in a country who have felt maligned and mistreated. Being "defensive" is a form of protection and protest, whether the protest is verbal or through actions. So if Israel is "defensive", you'd only need to look at the history of the country to see how it has experiences "offenses" against it and its people.
All the main reason was that God had told Israel that you will not have any peace, and so the tribes always attacked each other.
Attacked from all sides
Israel attacked Egypt in response to Egyptian denial of Israeli shipping through the Suez Canal.
Sennacherib and Shalmaneser (V) each attacked Israel in the north, several years apart.
Most of what they gained in 1948, when the UN drew up the map but the "Palestinians" rejected the whole notion of partition and attacked Israel.
Israel
1) In 1956, Israel attacked Egypt with the prompting of the United Kingdom and France. 2) In 1967, Israel attacked Egypt responding to an Egyptian blockade of Israel's southern port. All other wars that Israel has participated in have been brought about due to attacks on its land or its people first.
The Arab countries surrounding Israel have never wanted Israel to exist, and have attacked numerous times.
Israel
Israel.
Israel
They attacked Israel within days of its formal creation.