Israel began research on chemical, biological and nuclear weapons in 1948, determined never again to be put through another Holocaust. Their leaders called it “The Samson Option” from the story in Judges 16:28-30 where Samson collapsed the pillars holding up the house, killing nearly 3000 Philistine leaders and revellers with him in death. Should Israel ever reach the point where they feel their enemies could wipe Israel out as a nation, their goal is to rain nuclear bombs on the countries of all their enemies, ensuring all their enemies also die.
It was the French who provided nuclear expertise and constructed the reactor complex in Israel capable of large-scale plutonium production and reprocessing. In the early 1960s, Israel was able to go it alone, progressing rapidly through many secret operations, including several nuclear tests. After the U S discovered their secret in 1958, it became subject to continual discussions between the US and Israel. Because the US had sided with Russia over the Suez Canal war, Israel initially deceived the United States, then later they used their nuclear option as a bargaining chip in order to get US conventional arms supplies.
Israel had never admitted having a nuclear arsenal. In Dec 2008 Ehud Olmert let slip during an interview in Germany that Israel did indeed have nuclear weapons. Israel still doesn’t officially admitted it, but it is widely believed by experts in the field that Israel has a combination of between 300 & 400 nuclear fission (Atomic) bombs, and Nuclear Fusion (Thermonuclear) bombs, not all of which have been assembled, but which are ready for assembly at a moments notice. Israel’s four German built submarines are probably armed with nuclear devices with multiple warheads enabling them to strike anywhere in the world.
The rest are safely secreted around the Negev desert, in case of an unexpected enemy attack. Twice in the past these nuclear devices have been brought out and assembled ready for use. The first time was before the 1967 Six-Day War, when they believed their nuclear facility was at risk, and reportedly assembled several nuclear bombs. By the 1973 Yom Kippur War Israel had a number of sophisticated nuclear bombs, which they deployed them ready for use if required.