By 1969, U.S. Defense Secretary Melvin Laird believed that Israel might have a nuclear weapon that year.[61][62] Later that year, U.S. President Richard Nixon in a meeting with Israeli Prime Minister Golda Meir pressed Israel to "make no visible introduction of nuclear weapons or undertake a nuclear test program", so maintaining a policy of nuclear ambiguity.[63] Before the Yom Kippur War Peres nonetheless wanted Israel to publicly demonstrate its nuclear capability to discourage an Arab attack, and fear of Israeli nuclear weapons may have discouraged Arab military strategy during the war from being as aggressive as it could have been.[25]

His (Nasser) rhetoric of 1965 and 1966 about preventive war and Israeli nuclear weapons coupled with overflights of the Dimona rector contributed to the tensions that led to war.  The Egyptian Air Force claims to have first overflown Dimona and recognized the existence of a nuclear reactor in 1965. Of the 50 American HAWK antiaircraft missiles in Israeli hands, half ringed Dimona by 1965. Israel considered the Egyptian overflights of May 16, 1967 as possible pre-strike reconnaissance.  One source lists such Egyptian overflights, along with United Nations peacekeeper withdrawal and Egyptian troop movements into the Sinai, as one of the three “tripwires” which would drive Israel to war.  There was an Egyptian military plan to attack Dimona at the start of any war but Nasser vetoed it. He believed Israel would have the bomb in 1968.48  Israel assembled two nuclear bombs and ten days later went to war.  Nasser's plan, if he had one, may have been to gain and consolidate territorial gains before Israel had a nuclear option.  He was two weeks too late.

Shimon Peres had argued for a pre-war nuclear demonstration to deter the Arabs.  Arab strategies and war aims in 1967 may have been restricted because of a fear of the Israeli “bomb in the basement,” the undeclared nuclear option.  The Egyptians planned to capture an eastern strip next to the Suez Canal and then hold.  The Syrians did not aggressively commit more forces to battle or attempt to drive through the 1948 Jordan River border to the Israeli center.  Both countries seemed not to violate Israel proper and avoided triggering one of the unstated Israeli reasons to employ nuclear weapons.

The policy and practice of nuclear opacity was codified in 1969 in an extraordinary secret accord between Israeli Prime Minister Golda Meir and U.S. President Richard Nixon. Although this agreement has never been openly acknowledged or documented, its existence was revealed in 1991 by the Israeli journalist Aluf Benn, and more information came out in some recently declassified memos regarding Nixon's 1969 meeting with Meir written by Nixon's national security adviser, Henry Kissinger. According to the Nixon-Meir pact, as long as Israel did not advertise its possession of nuclear weapons by publicly declaring or testing them, the United States would tolerate and shield Israel's nuclear program.

Concerned about pushback from friends and foes, Israel shrouded its nuclear enterprise from the earliest days. Israel and the Bomb reveals that, in May 1963, Prime Minister David Ben-Gurion, the father of the weapons program, attempted to pull the wool over the eyes of a skeptical President John F. Kennedy, who was determined to halt Israel’s nuclear quest. Ben-Gurion wrote, “In our conversations in 1961 I explained to you that we were establishing nuclear training and reactor in Dimona with French assistance. This assistance has been given on condition that the reactor will be devoted exclusively to peaceful purposes. I regard this condition as absolutely binding.” Kennedy remained unconvinced and continued to press the Israelis on the program until his death.

1. The Domestic Sources
1.(1).
 
The domestic sources of opacity involve attitudes of individuals, deliberations and debates among elite groups inside and outside the government, and broader societal-cultural attitudes regarding nuclear weapons. Prior to the disclosure of the Dimona reactor in December 1960, during the phase of complete secrecy, the attitudes of David Ben-Gurion--Israel's first prime minister and the father founder of the nuclear project--played a crucial role in shaping the contours of Israel's nuclear policy. Though Ben-Gurion had no sense of the idea of nuclear opacity, let alone the terminology, his instinctive attitudes on this matter proved fateful for opacity. His dual role as minister of defense and prime minister allowed him to make all the big decisions on his own. Until the deal with France was finalized in late 1957 there were hardly any political-domestic consultations. When the big decisions concerning Dimona and related issues were made in 1957-58 Ben-Gurion shared with his senior colleagues only the minimum necessary; it was only discussed on a "need to know" basis.
1.(2).
 
Secrecy, concealment and vagueness were Ben-Gurion's traits in dealing with this subject, at home and abroad, for the entire period that he was Israel's prime minister. Michael Bar Zohar, one of Ben-Gurion's biographers, elaborated on his tendency to avoid discussing long-term policy objectives, unless it was absolutely necessary and unavoidable.5 Shimon Peres focused on this general point with regard to the nuclear issue when he commented on Ben-Gurion's reluctance to "nail down" Dimona's long-term objectives.6 In another occasion Peres recalled that in the days of the project "we never talked about nuclear weapons, not even in internal discussions, we always talked about an 'option.'" Even with his close political colleagues who knew something about the project, Ben-Gurion was vague about the security motivation of the Dimona project, making ambiguous references to the need to develop a national nuclear energy infrastructure in a manner that would create a "nuclear option" for both civilian and military applications available for future decision-makers.
1.(3).
 
Apparently, Ben-Gurion himself was not clear in his own mind in those days how far Israel should go with its nuclear pursuits, and what posture he should pursue. So he improvised one step at a time. To discuss long-term goals prematurely could compromise the security of the entire young project, at home and abroad. This reluctance at the very highest level to "nail down" long-term objectives was among the early tenets of opacity. To this day, this taboo has persisted.
1.(4).
 
Another important tenet of opacity involves the strategy Ben-Gurion chose to present the project to the United States in December 1960. Ben-Gurion chose the path of denial: he denied that Dimona was about security; he presented Dimona as exclusively civilian-peaceful infrastructure. Why did Ben-Gurion choose to be less-than-honest from the very start with the United States? It may be that part of the answer resides in Ben-Gurion's domestic situation. The American exposure came in a most unfortunate time for Ben Gurion: at the height of the Lavon Affair.7 Though the two issues were substantially unrelated, they were politically related. In December 1960 Ben-Gurion was a weakened national leader, exhausted by the Lavon Affair and by the bitter generational struggle over leadership that it produced. The Dimona project was an item in this political struggle. His weakness at home was probably a factor that shaped his choice of strategy in response to the American demand for explanation about Dimona. Constrained by earlier assurances he had given to Charles de Gaulle and by his struggle at home, Ben-Gurion was determined to avoid a path of confrontation with the United States over Dimona. He could not control the outcome of such confrontation, and he recognized that it could be disastrous both for the Dimona project and his own leadership. Denial involved no immediate public confrontation with the United States.
1.(5).
 
Ben-Gurion's strategy of denial, however, had profound consequences on Israel's nuclear discourse. It created a climate that made public nuclear debate difficult, if not impossible. To criticize Ben-Gurion on the Dimona project would imply that his statement to the Knesset was not truthful; this could be damaging to Israel and would be looked upon as an unpatriotic act. Virtually all Zionist parties, left and right alike, felt inhibited to voice reservations in public. For one thing, due to secrecy and the technological complexity of the issue, few were competent and informed to debate the issue. For another thing, even those who understood Ben-Gurion's interest in a nuclear option were instinctively reluctant to debate the issue in public. Notwithstanding reservations about how the project had been decided and executed, Zionist parties were committed to the imperative of Kdushar Ha-bitachon--the sanctity of security. For those few who did insist on debating the issue in public, the procedures of the Military Censor made it difficult for them to state their case properly. All in all, the taboo was more self-imposed than imposed by law. This taboo, too, is among the most powerful societal sources of opacity, and has endured the present time.
1.(6).
 
Around 1962, more than four years after the Dimona project had been initiated, the hidden nuclear dilemma resurfaced politically in two ways. First, the Knesset was no longer ready to be bypassed and ignored. Parliamentarian leaders demanded that Ben-Gurion share information with them on a strictly secret basis. Ben-Gurion agreed and a seven-member sub-committee, made of the leaders of the major parties, was secretly formed to oversee the nuclear project. It became the most distinguished and prestigious Knesset sub-committee. By sharing sensitive information (mostly financial and technological) with this committee on a strictly secret basis (members were not even allowed to take notes in those briefings), Ben-Gurion assured that public debate would not take place. Being sworn to secrecy, these Knesset members became, for all practical purposes, the project's gatekeepers, they almost never questioned the principles, they never discussed the issue in public, and they made the issue off-limits to domestic politics. This fundamental pattern, too, was a domestic source of opacity.
1.(7).
 
The second action Ben-Gurion took in 1962 was opening the nuclear dilemma to a selected group of Israeli defense leaders, past and present. The issue at stake was whether Israel should make fundamental changes in its military doctrine and force structure: whether Israel should invest its limited sources on non-conventional capabilities (nuclear, missiles) or continue to modernize its conventional forces. The timing of those high-level discussions was triggered in part by Egypt's missile project and by the necessity to make basic decisions since Dimona was moving towards completion. By that time there already had been a quiet but fierce doctrinal debate between those who supported investment in modernizing the conventional forces (armor, tactical air force) and those who were advocating revolutionary shift to non-conventional technologies, missiles and nuclear. In 1962, Ben-Gurion decided to conduct a seminar-like debate between the two schools before a decision was made. Peres and Dayan represented the pro-nuclear view, advocating what Peres called in those days "the doctrine of self-reliance" and the view that for the long-run Israel would not be able to compete in a conventional arms race with the Arabs. Ultimately, nuclear weapons would force the Arabs to abandon hopes of settling the conflict by military means. Allon and Galili represented the other view, disagreeing with Dayan's pessimism and warned of the danger in applying the nuclear deterrence calculus to the Israeli context.
1.(8).
 
Ben-Gurion was reportedly reluctant to make a final doctrinal choice. He left the big issue open, while making small decisions. For the time being Israel would not invest its limited funds in order to shift towards nuclear doctrine. Instead, it would continue to invest most of its funds on strong tactical air force and tanks. Still, Ben-Gurion initiated a missile project and continued with the plans to finish the nuclear infrastructure but not as a crash program. It turned out that the way Ben-Gurion handled the dilemma in 1962-63 had a lasting effect, much beyond the particulars of the time. This way of resolving the dilemma by default and post-ponement, while in the meantime maintaining the conventional balance and treating the nuclear option as insurance, became the mark of Israel's pattern of proliferation. Israel had been reluctant to accept the nuclear reality through the front door. Inevitably, it created a situation in which the nuclear issue sneaked in quietly through the back door. This was another early source of Israeli opacity.
1.(9).
 
The seeds of opacity that had been planted during the Ben-Gurion era deepened during the Eshkol era. The nuclear issue remained greatly isolated and insulated from the rest of the domestic politics agenda. Eshkol, like his predecessor, made nuclear decisions in consultations with a handful of ministers and aides. Until his resignation in 1965, Peres was still the man in charge of the project under the prime minister. Later, Zvi Dinstein replaced him, while Galili, Allon, Eban and Rabin became among Eshkol's closest advisors. Eshkol rarely brought the nuclear issue to the cabinet, except to approve his plans for its reorganization in 1966.

The second generic source that shaped Israel's nuclear posture was interaction with outside powers. In the period prior to 1970, two international powers were especially important to that effort. France was the country that introduced Israel not only to nuclear technology but also the delicate art of opaque nuclear politics. The United States was the superpower that was in search of its own global non-proliferation policy at the time that Israel was making its first steps in this area. In retrospect, the United States shaped Israeli opacity more than any other state. In return, the United States was Israel's unknowing partner in the making of opacity.

2.2. The United States
2.2.(1).
 
If France was the nation from which Israel had learned how a democracy can go nuclear opaquely, the United States was the superpower whose response to Israel's nuclear program greatly shaped the way Israel stumbled into opacity. The historical record indicates that Israel's unique political way of acquiring nuclear capability, and the mode of nuclear proliferation it developed, was closely related to the evolution of American non-proliferation policy in the 1960s.
2.2.(2).
 
The United States was not in a position to stop the Israeli nuclear program, but the American security/nuclear dialogue significantly determined the political mode under which Israel went nuclear. Israel went nuclear opaquely, not overtly, in a way that carefully considered American policies and deliberately avoided defying American non-proliferation policy. During the 1960s, while four American administrations came and went, the United States and Israel groped for answers that would satisfy strategic needs, national goals and political requirements. The search continued for nearly a decade. Three pairs of American-Israeli leaders made the critical and distinct stages in that search: Kennedy-Ben-Gurion, Johnson-Eshkol and Nixon-Meir. In a kind of Hegelian-like dialectical path, the search progressed through three distinct political stages, for each pair of interlocutors: confrontation, ambiguity and reconciliation. Israel's nuclear opacity was the ultimate answer to this decade-long search.
2.2.(3).
 
In turn, the Israeli nuclear case was an important factor in the shaping and evolution of American non-proliferation policy throughout the 1960s. In a sense, Israel was the first case of nuclear weapons proliferation with which the United States had to contend, beyond Russia, Britain, France and China, at a time when the United States had not yet developed a coherent non-proliferation policy. Israel was a case of a friendly and small state surrounded by bigger enemies and (unlike Germany) outside the sphere of superpower containment. Moreover, unlike the cases of the Soviet Union, the UK, and France (and later China or India), Israel did not aspire to the status of the great powers. And, most significantly, Israel enjoyed strong domestic support in America. The challenge of how to apply the long-held American opposition to the spread of nuclear weapons to the complexity of the Israeli case had lasting effect that went far beyond the Israeli case. The Israeli case was an important learning experience for those three American administrations in their search for a coherent non-proliferation policy.
2.2.(4).
 
The Israeli nuclear case evolved in the 1960s as the Kennedy and Johnson administrations grappled to form American non-proliferation policy aiming at creating a non-proliferation order based on international treaty. Israel was a key state for the evolution of American ideas about non-proliferation. Israel's nuclear posture evolved in the 1960s in interaction with the evolution of the U.S. non-proliferation policies. Viewed in this way, opacity came into being as a joint American-Israeli effort to respond to their respective dilemmas, as the co-evolution of Israel's proliferation policy and American non-proliferation policy. The complexity of the Israeli case was an important impetus for the United States in seeking the NPT. By the same token, the specter of such a treaty was an important factor in moderating Israeli nuclear ambitions.
2.2.(5).
 
On at least eight occasions during the 1960s, the United States came to the point of a confrontation or near-confrontation with the Israeli government over Israel's nuclear program. The first time was in December 1960, when the Eisenhower administration revealed publicly the existence of Israel's plans to build a nuclear reactor in Dimona and demanded Israeli explanations and reassurances about the reactor's peaceful purpose. Ben-Gurion responded by providing public and private assurances that the Dimona reactor was for "peaceful purposes." But no agreement about American visits to Dimona was struck. That confrontation was short-lived because it started in the last few weeks of the departing Eisenhower administration. The challenge was left to the incoming Kennedy administration.
2.2.(6).
 
After it took office in January 1961, the Kennedy administration dealt with the political sensitivity and technical reality of the Israeli nuclear program as a long-term policy issue. If the United States wanted to draw the line on nuclear proliferation, as Kennedy believed it should, the Israeli program had to be curbed. Kennedy found himself in a dilemma. He had a deep personal commitment to the cause of nuclear non-proliferation, but he also had a strong commitment to the security and well-being of Israel. This was a time when the United States had not yet developed a coherent global nonproliferation policy. The Kennedy administration found itself searching for a nonproliferation policy vis-à-vis Israel while other allies of the United States--the UK and France--were developing their own nuclear arsenals.
2.2.(7).
 
President Kennedy twice tried to intervene in Israel's nuclear affairs, but confrontation was averted in each case through delicate quiet diplomacy at the highest level. In early 1961, shortly after he took office, Kennedy was determined to obtain verifiable assurances, by way of American visits on site, of the peaceful nature of the Dimona project. Ben-Gurion agreed and invited two prominent American scientists to visit Dimona. The visit revealed no indications of a weapons program. It was also a precedent. In the wake of the scientists' positive report the two leaders met in New York on May 30,1961. No better example of that high-level compromise exists than the discussion of nuclear issues at that meeting. The two leaders wanted to avoid a confrontation, and each had a sense of his own political limits, at home and abroad. Kennedy did not raise questions which went beyond Ben-Gurion's tentative assurances on the peaceful purpose of the Dimona reactor. Ben-Gurion respected Kennedy's political needs and did not question American non-proliferation policy as it applied to Israel. Both nations thereby planted the seeds of opacity.8
2.2.(8).
 
The meeting in New York presaged the future by setting, unintentionally, the parameters by which both nations would conduct their dealings on the nuclear issue. The verbal understandings reached at that meeting allowed the nuclear issue to be left off the bilateral agenda for almost two years. The issue of Dimona, however, resurfaced in the spring of 1963, as the Dimona reactor was about to become operational. Kennedy was focusing on the problem of global proliferation in connection with the anticipated negotiation of a test ban treaty, what became the Partial Test Ban Treaty (PTBT) of July 1963. Ben-Gurion's pressure on the United States for American security assurances to Israel was his response to Kennedy's pressure on the nuclear issue. Delaying his response to Ben-Gurion's request for U.S. security guarantees, Kennedy wrote of his concern about the introduction of advanced weaponry (nuclear arms and ballistic missiles) into the Middle East. This dramatic correspondence between the two leaders continued until Ben-Gurion's resignation on 16 June 1963, the day on which Kennedy's tough letter was to be delivered to him. The letter was never delivered to Ben-Gurion because on that very day he resigned from office.9
2.2.(9).
 
However, Kennedy did not cease his pressure on Israel. Prime Minister Levi Eshkol took office in late June 1963 during the most severe American-Israeli confrontation over the nuclear issue. Days after he took office, he received one of the toughest messages an Israeli prime minister had ever received from an American president, a slightly modified version of Kennedy's letter to Ben-Gurion. Kennedy demanded of Eshkol a verified implementation of the arrangements Ben-Gurion had agreed to in principle, which would confirm the peaceful purpose of Dimona. The key to these arrangements was Kennedy's demands for "semi-annual" visits by American scientists to Dimona. After weeks of a near-crisis situation, on 19 August 1963, Eshkol proposed a formula, allowing American visits in Dimona, which appeared to satisfy Kennedy's demands. Eshkol's formula, however, left somewhat vague the issue of timing and exact nature of the American visits to Dimona. Once again, a showdown was averted, as Eshkol was able to offer a compromise that seemed to meet Kennedy's demands.10
2.2.(10).
 
Although the nuclear understandings reached in August 1963 were vague, they proved lasting and decisive. Lyndon Johnson, who succeeded Kennedy in November 1963, had to implement the Kennedy-Eshkol understanding. Johnson was not as personally committed as his predecessor to the cause of nuclear non-proliferation. The Johnson administration pressed Eshkol to allow it to reassure Nasser on Dimona during Eshkol's first visit in Washington in 1964. In the coming years it made at least two high-level attempts to place Dimona under International Atomic Energy Agency (IAEA) safeguards--in the Harriman-Komer visit to Israel in 1965 and in connection to the negotiations over the sale of Sky hawks in 1966--but it backed off in face of Israeli resistance. Eshkol was not ready to go beyond his ambiguous pledge that Israel would not be the first country to introduce nuclear weapons into the Middle East and the Johnson administration had no recourse but to accept it. The era of confrontation was replaced with the era of ambiguity.
2.2.(11).
 
The seventh time that Israel and the United States had a confrontation over the nuclear issue was during 1968, Johnson's last year in office and the year in which the NPT was signed. The Johnson administration exerted pressure on Israel to sign the NPT. At first Israel seemed to acquiesce in the American request, but by summer 1968 it became clear that Jerusalem was determined not to sign the treaty. The issue came to a point of confrontation in late 1968 as Israel negotiated for the first sale of Phantoms. The American pressure was mounting, but on the eve of the presidential election in November 1968 Johnson decided to put an end to the pressure. Israel received the Phantoms and did not sign the NPT.
2.2.(12).
 
In July 1969 the United States conducted the last visit to the Dimona site. Later that year, Prime Minister Golda Meir reached a new kind of tacit understanding with President Richard Nixon which ended the American visits in Dimona. According to this understanding, Israel refrained from making public reference to its nuclear capability--no declaration, no testing--while the United States looked the other way at the Israeli nuclear case. With this understanding, nuclear opacity emerged in its full-blown form. This was the transition from ambiguity to reconciliation.
2.2.(13).
 
As a whole, the American-Israeli security/nuclear dialogue throughout the 1960s evolved gradually around three fundamental axes: (a) supply of American conventional weapons to Israel; (b) American assurances on Israeli security; (c) inhibitions on Israel's nuclear program. A few times they came to the verge of collision but always a public showdown was avoided because ultimately neither party was interested in that. These confrontational and near-confrontational episodes created a binational learning curve. It was a process of trial and error, largely tacit, through which both the United States and Israel learned how to cope with the Israeli nuclear case.

L'Iran a interrompu ses négociations avec les grandes puissances pour dénoncer la décision des Etats-Unis d'étoffer sa liste noire des entreprises soupçonnées de violer les sanctions américaines contre Téhéran, un geste "contraire à l'esprit" de l'accord de Genève conclu fin novembre.