Israel began investigating the nuclear field just one year after its 1948 founding and with French support secretly began building a nuclear reactor and reprocessing plant in the late 1950s. Although Israel first built a nuclear weapon in 1967-68 it was not publicly confirmed from the inside until Mordechai Vanunu, a former Israeli nuclear technician, revealed details of the program to the British press in 1986. Israel is currently believed to possess between 75 to 200 nuclear warheads with the ability to deliver them by ground, aircraft, and submarine.
In early 1952 HEMED was moved from the IDF to the Ministry of Defense and was reorganized as the Division of Research and Infrastructure (EMET). That June, Ernst David Bergmann, the chief of research at the Defense Ministry and Prime Minister David Ben Gurion's scientific advisor, was appointed by Ben-Gurion to be the first chairman of the Israel Atomic Energy Commission (IAEC). HEMED GIMMEL was renamed Machon 4 during the transfer, and was used by Bergmann as the "chief laboratory" of the IAEC; by 1953, Machon 4, working with the Department of Isotope Research at the Weizmann Institute, developed the capability to extract uranium from the phosphate in the Negev and new technique to produce indigenous heavy water. Bergmann, who was interested in increasing nuclear cooperation with the French, sold both patents to the Commissariat à l'énergie atomique (CEA) for 60 million francs. Although they were never commercialized, it was a consequential step for future French-Israeli cooperation. At the same time Israeli scientists were also observing France's own nuclear program, and were the only foreign scientists allowed to roam "at will" at the nuclear facility at Marcoule.
After US President Dwight Eisenhower announced the Atoms for Peace initiative, Israel became the second country to sign on (following Turkey), and signed a peaceful nuclear cooperation agreement with the United States on 12 July 1955. This culminated in a public signing ceremony on 20 March 1957 to construct a "small swimming-pool research reactor in Nachal Soreq," which would be used to shroud the construction of a much larger facility with the French at Dimona.
This deal was finalized on 3 October 1957 in two agreements: one political that declared the project to be for peaceful purposes and specified other legal obligations, and one technical that described a 24 megawatt EL-102 reactor. The one to actually be built was to be two to three times as large and be able to produce 22 kilograms of plutonium a year.
In 1959 Israel bought 20 tons of heavy water from the UK, with the Norwegian company Noratom acting as a broker, and the nuclear reactor at Dimona went critical in 1962. By 1965 the Israeli reprocessing plant was completed and ready to convert the reactor's fuel rods into weapons grade plutonium.
Israel is believed to have begun full scale production of nuclear weapons following the 1967 Six-Day War, although it may have had bomb parts earlier. A CIA report from early 1967 stated that Israel had the materials to construct a bomb in six to eight weeks and some authors suggest that Israel had two crude bombs ready for use during the war. According to US journalist Seymour Hersh, everything was ready for production at this time save an official order to do so. Moshe Dayan, then Defense Minister, convinced the Labor Party's economic boss Pinchas Sapir of the value of commencing the program by giving him a tour of the Dimona site in early 1968, and soon after Dayan decided that he had the authority to order the start of full production of 4 to 5 nuclear warheads a year. Hersh stated that it is widely believed that the words "Never Again" were welded, in English and Hebrew, onto the first warhead.
In order to produce plutonium the Israelis needed a large supply of uranium ore, some of which was procured by the Mossad on the pretense of buying it for an Italian chemical company in Milan. Once the uranium was shipped from Antwerp it was transferred to an Israeli freighter at sea and brought to Israel. The orchestrated disappearance of the uranium, named Operation Plumbat, became the subject of the 1978 book The Plumbat Affair.
Estimates as to how many warheads Israel has built since the late 1960s have varied, mainly based on the amount of fissile material that could have been produced and on the revelations of Israeli nuclear technician Mordechai Vanunu. The CIA believed that the number of Israeli nuclear weapons stayed from 10 to 20 from 1974 through the early 1980s. Vanunu's information in October 1986 said that based on a reactor operating at 150 megawatts and a production of 40 kg of plutonium per year, Israel had 100 to 200 nuclear devices. Furthermore, Vanunu revealed that between 1980-1986 Israel attained the ability to build thermonuclear weapons. By the mid 2000s estimates of Israel's arsenal ranged from 75 to 200 nuclear warheads.
Several reports have surfaced claiming that Israel has some uranium enrichment capability at Dimona. Vanunu asserted that gas centrifuges were operating in Machon 8, and that a laser enrichment plant was being operated in Machon 9 (Israel holds a 1973 patent on laser isotope separation). According to Vanunu, the production-scale plant has been operating since 1979-80. The scale of a centrifuge operation would necessarily be limited due to space constraints. Laser isotope separation, however, if developed to operational status, could be quite compact. If highly enriched uranium is being produced in substantial quantities, then Israel's nuclear arsenal could be much larger than estimated solely from plutonium production. Uranium enrichment could also be used to re-enrich reprocessed uranium into reactor fuel to more efficiently use Israel's uranium supply.
In 1991 alone, as the Soviet Union dissolved, nearly 20 Jewish top Soviet scientists reportedly emigrated to Israel, some of whom had been involved in operating nuclear power plants and planning for the next generation of Soviet reactors. In September 1992, German intelligence was quoted in the press as estimating that 40 Soviet nuclear scientists had emigrated to Israel since 1989.
This flurry of media reporting led Ben-Gurion to make the only statement ever by an Israeli Prime Minister about Dimona. On December 21 he announced in front of the Knesset that they were building a 24 megawatt reactor "which will serve the needs of industry, agriculture, health, and science," and that it "is designed exclusively for peaceful purposes.
The first extensive details of the weapons program came in the London based Sunday Times on 5 October 1986, which printed information provided by Mordechai Vanunu, a technician formerly employed at the Negev Nuclear Research Center near Dimona. For publication of state secrets Vanunu was kidnapped by the Mossad in Rome, brought back to Israel, and sentenced to 18 years in prison for treason and espionage. Although there had been much speculation prior to Vanunu's revelations that the Dimona site was creating nuclear weapons, Vanunu's information indicated that Israel had also built thermonuclear weapons.
In a December 2006 interview, Israeli Prime Minister Ehud Olmert came close to breaking with Israel's policy of nuclear opacity, saying that Iran aspires "to have a nuclear weapon as America, France, Israel and Russia. Olmert's office later said that the quote was taken out of context; in other parts of the interview, Olmert refused to confirm or deny Israel's nuclear weapon status.
Israel's nuclear doctrine is shaped by its lack of strategic depth: a subsonic fighter jet could cross in four minutes the from the Jordan River to the Mediterranean Sea. It additionally relies on a reservist-based military which magnifies civilian and military losses in its small population. Israel tries to compensate for these weaknesses by emphasising intelligence, manoeuverability and firepower.
As a result, its strategy is based on the premise that it cannot afford to lose a single war, and thus must prevent them by maintaining deterrence, including the option of preemption. If these steps are insufficient, it seeks to prevent escalation and determine a quick and decisive war outside of its borders.
Strategically, Israel's long-range missiles, nuclear capable aircraft, and possibly its submarines present an effective second strike deterrence against unconventional and conventional attack, and if Israel's defences fail and its population centres be threatened, the Samson Option, an all out attack against an adversary, would be employed. Its nuclear arsenal can also be used tactically.
Although nuclear weapons are viewed as the ultimate guarantor of Israeli security, as early as the 1960s the country has avoided building its military around them, instead pursuing absolute conventional superiority so as to forestall a last resort nuclear engagement.
According to historian Avner Cohen, Israel first articulated an official policy on the use of nuclear weapons in 1966, which revolved around four "red lines" that could lead to a nuclear response:
1. A successful Arab military penetration into populated areas within Israel's post-1949 (pre-1967) borders.
2. The destruction of the Israeli Air Force.
3. The exposure of Israeli cities to massive and devastating air attacks or to possible chemical or biological attacks.
4. The use of nuclear weapons against Israeli territory.
Israeli military and nuclear doctrine increasingly focused on preemptive war against any possible attack with conventional, chemical, biological or nuclear weapons, or even a potential conventional attack on Israel's weapons of mass destruction.
Louis René Beres, who contributed to Project Daniel, urges that Israel continue and improve these policies, in concert with the increasingly preemptive nuclear policies of the United States, as revealed in the Doctrine for Joint Nuclear Operations.
After Iraq attacked Israel with Scud missiles during the 1991 First Gulf War, Israel went on full-scale nuclear alert and mobile nuclear missile launchers were deployed. In the build up to the United States 2003 invasion of Iraq, there were concerns that Iraq would launch an unconventional weapons attack on Israel. After discussions with President George W. Bush then Israeli Prime Minister Ariel Sharon warned "If our citizens are attacked seriously - by a weapon of mass destruction, chemical, biological or by some mega-terror attack act - and suffer casualties, then Israel will respond." Israeli officials interpreted President Bush's stance as allowing a nuclear Israeli retaliation on Iraq, but only if Iraq struck before the US military invasion.
Alone or with other nations, Israel has used diplomatic and military efforts as well as covert action to prevent other Middle Eastern countries from acquiring nuclear capabilities.
On 7 June 1981, Israel launched a preemptive air strike against Saddam Hussein's breeder reactor in Osirak, Iraq, in Operation Opera. The Mossad is also said to have assassinated professor Gerald Bull, an artillery expert, who was allegedly building a massive cannon or "super gun" for Saddam Hussein in the 1980s, which was capable of delivering a tactical nuclear payload.
On 6 September 2007, Israel launched an air strike dubbed Operation Orchard against a target in the Deir ez-Zor region of Syria. While Israel refused to comment, unnamed US officials said Israel had shared intelligence with them that North Korea was cooperating with Syria on some sort of nuclear facility. Both Syria and North Korea denied the allegation and Syria filed a formal complaint with the United Nations. Journalist Seymour Hersh speculates that this air strike may have been intended as a trial run for striking alleged Iranian nuclear weapons facilities. On January 7, 2007 The Sunday Times reported that Israel had drawn up plans to destroy three Iranian nuclear facilities with low-yield nuclear bunker-busters that would be launched by aircraft through "tunnels" created by conventional laser-guided bombs. These tactical nuclear weapons would then explode underground to reduce radioactive fallout. Israel denied the specific allegation. However, its military leaders admit that it rules out no option. The death of the Iranian physicist Ardeshir Hassanpour, who may have been involved in the nuclear program, has been reported by the intelligence group Stratfor to have been a Mossad assassination. Iran is currently conducting atomic research that Israel fears is aimed at building a nuclear weapon. Israel has pressed for United Nations economic sanctions against Iran, and has repeatedly threatened to launch a military strike on Iran if the United States does not do so first.
In 1996 the United Nations General Assembly passed a resolution calling for the establishment of a nuclear-weapon-free zone in the region of the Middle East. Arab nations and annual conferences of the International Atomic Energy Agency (IAEA) repeatedly have called for application of IAEA safeguards and the creation of a nuclear-free Middle East. Arab nations have expressed their disgust that the United States practices a double standard in criticizing Iran's nuclear program while ignoring Israel's possession of nuclear weapons. According to a statement by the Arab League, Arab states will withdraw from the NPT if Israel acknowledges having nuclear weapons and then does not open its facilities to international inspection and destroy its arsenal.