|Nuclear program start date||mid-to-late 1950s|
|First nuclear weapon test||Unknown; possible joint nuclear test with South Africa on September 22, 1979|
|First fusion weapon test||Unknown|
|Last nuclear test||Unknown|
|Largest yield test||Unknown|
|Current stockpile (usable and not)||estimated 80–400 warheads|
|Current strategic arsenal||Unknown|
|Cumulative strategic arsenal in megatonnage||Unknown|
|Maximum missile range||11,500 km with 1000 kg payload; probably significantly greater with smaller payload (Jericho III)|
Israel is widely believed to possess nuclear weapons and to be the sixth country in the world to have developed them, allegedly having built its first nuclear weapon in December 1966. It is one of four nuclear-armed countries not recognized as a Nuclear Weapons State by the Nuclear Non-Proliferation Treaty (NPT), the others being India, Pakistan and North Korea. Israel maintains a policy known as “nuclear ambiguity” (also known as “nuclear opacity”). Israel has never officially admitted to having nuclear weapons, instead repeating over the years that it would not be the first country to “introduce” nuclear weapons to the Middle East, leaving ambiguity as to whether it means it will not create, will not disclose, will not make first use of the weapons or possibly some other interpretation of the phrase. The “not be the first” formulation goes back to the Eshkol–Comer (sic) memorandum of understanding made between Israel and the United States on March 10, 1965, which contained Israel’s written assurance for the first time that it would not be the first to introduce nuclear weapons in the Middle East. Israel has refused to sign the NPT despite international pressure to do so, and has stated that signing the NPT would be contrary to its national security interests.
Additionally, Israel has made extensive efforts to deny other regional actors the ability to acquire their own nuclear weapons. The counter-proliferation, preventive strike Begin Doctrine added another dimension to Israel’s existing nuclear policy. Israel remains the only country in the Middle East believed to possess them.
Israel started investigating the nuclear field soon after its founding in 1948 and with French support secretly began building a nuclear reactor and reprocessing plant in the late 1950s in Dimona. Israel is alleged to have built its first nuclear weapon in December 1966, but it is not publicly confirmed. In 1986,  Mordechai Vanunu, a former Israeli nuclear technician, provided explicit details and photographs to the Sunday Times of a nuclear weapons program in which he had been employed for nine years, “including equipment for extracting radioactive material for arms production and laboratory models of thermonuclear devices.” In 1987, an unclassified US DoD report  (released in February 2015 in response to a FOIA request) stated that “As far as nuclear technology is concerned, the Israelis are roughly where the U.S. [w]as in the fission weapon field in about 1955 to 1960. It should be noted that the Israelis are developing the kind of codes which will enable them to make hydrogen bombs.”
Estimates as to the size of the Israeli nuclear arsenal vary between 75 and 400 nuclear warheads. It is estimated that the Israel nuclear deterrent force has the ability to deliver them by intermediate-range ballistic missile, intercontinental ballistic missile, aircraft, and submarine-launched cruise missile. The Stockholm International Peace Research Institute estimates that Israel has approximately 80 intact nuclear weapons, of which 50 are for delivery by Jericho II medium-range ballistic missiles and 30 are gravity bombs for delivery by aircraft.
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