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Yitzhak "Ya’tza" Ya’akov

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Interview with Yitzhak "Ya’tza" Ya’akov  


Yitzhak Ya’acov (1926-2013), known his entire life by the nickname “Ya’tza,” was a Brigadier General in the Israeli Defense Forces (IDF) in charge of weapons research and development (R&D). He was at the center of Israel’s first nuclear alert on the eve of the 1967 war.    

Born in Tel Aviv in 1926, Ya’tza joined the Palmach, the elite special fighting force of the Haganah (pre-state militia) in 1944, and in 1948, during Israel’s “War of Independence,” fought on the Jerusalem front, starting as platoon commander and ending the war as an acting battalion commander.

After the 1948 war, Ya’tza earned engineering degrees as an IDF officer, first from the Technion (Israel Technological Institute) and later from the Massachusetts Institute of Technology (MIT).  He served in various roles within the IDF’s R&D establishment.  In 1963, upon his return from MIT, as a newly promoted colonel, Ya’tza was appointed head of the Weapons Means department (Hebrew acronym, AMLACH) within the IDF General Staff (AGAM).  In that capacity, he served as the senior liaison between the IDF and all the civilian defense R&D entities, including the nuclear project. He held that position during the crisis in May-June 1967 that led to the Six Day War. 

In those days Ya’tza initiated, drafted, and promoted a military plan, code-named “Shimshon [Samson] Operation,” to demonstrate nuclear capability, via detonation of a nuclear device, in a desolate site in the Eastern Sinai desert.  This super-secret contingency plan did not even come close to execution, but in retrospect it was a most fateful moment in Israel’s nuclear history. Many regard it as the single moment when Israel crossed the nuclear threshold.     

In September 1968, Ya’tza was appointed Deputy Chief Scientist of the Israeli defense establishment (both military and civilian).  In 1972, he founded and ran the Weapons Research and Development (Hebrew acronym, MOP) unit shared by both the IDF and the Israeli Ministry of Defense.  Ya’tza completed this assignment in late September 1973, just days prior to the Yom Kippur War. He formally retired from the IDF in April of 1974.

From 1974 to 1978, Ya’tza served as the Chief Scientist at the Ministry of Trade and Commerce. In that capacity, he invented the concept of “technological greenhouses” as a means to promote high-tech starts up in Israel.  In 1979, he left government work and moved to the private sector as a venture capitalist promoting Israeli high tech. In the early 1980s, he moved to New York City where he continued his entrepreneurial work.   

By the late 1990s, Ya’tza found himself haunted by his memories of the 1967 Shimshon Operation.  In 1997, he wrote a fictionalized novel titled, “Atomic Incident,” based on those events and a year later he started writing his memoirs.  Those manuscripts were never published.   

In late 2000, Ya’tza gave an interview to an Israeli journalist, Dr. Ronen Bergman, in which he discussed his 1967 experience. The interview was submitted to the military censor in Israel who banned its publication.  The prohibited interview was also passed to the Security Office at the Ministry of Defense (MALMAB) who issued a security investigation of Ya’tza. 

On March 28, 2001, Ya’tza was secretly arrested at Ben Gurion International Airport.  Subsequently, Ya’tza was indicted, charged, and tried on two national security offenses: the first, and more severe charge, being “high espionage,” passing secret information with intent to harm national security, while the second, lighter one, was disclosing secret information to unauthorized people.  Ya’tza was eventually acquitted by the district court of the more serious offense, but found guilty of the lesser charge.  He was given a two-year suspended sentence and was immediately released. His arrest and trial became known in Israel as the “Ya’tza Affair.”

In 2011, he published a new memoir in Israel.

Ya’tza died in Tel Aviv on March 25, 2013, a day after his 87th birthday. 

Interview Notes by Avner Cohen 

The transcript is extracted from the first – and the most comprehensive – interview in a series of several I conducted with Brig. General (Ret.) Yitzhak Ya’akov (Ya’tza) during the summer and fall of 1999 and early 2000. Most of our meetings took place at Ya’tza’s mid-town, New York apartment, though at one point we both travelled to Austin, Texas and met with Yuval Ne’eman to share his own historical perspective. This interview, which lasts about two hours and ten minutes and was conducted in Hebrew, took place probably in August 1999. 

The initial purpose of the interview was to create a taped testimony of Ya’tza’s recollection of those extraordinary events of 1967.  The interview was not initially intended for publication, but rather to serve as raw research material for future work.  

Now, however, for the 50th anniversary of the 1967 War, we thought that this crude interview has a unique historical quality. It tells a remarkable story from the perspective of a senior IDF officer directly involved in one of the global nuclear history’s least known moments, indeed a story that was never before told in public.   

The transcript – extracted from the original audio tape and later converted to digital – is now part of the “Avner Cohen Collection,” for which the Nuclear Proliferation International History Project (NPIHP) serves as custodian.  The audio was first transcribed in Hebrew, then translated to English, virtually verbatim, by NPIHP interns, Ronen Plechnin and David Najmi, in 2012-13. In February-March, 2017, I made a final edit of the English transcript by reviewing the original Hebrew tape and then comparing it again with both the Hebrew and English transcripts.   

This transcript remains a very close reflection of the original tape.  However, on a few occasions, when the conversation moves to areas deemed unfit for publication – for reasons of privacy, clarity, relevance or national security – some lines were deleted here and there.  All the points where deletions were made are clearly marked in the transcript.  Still, this nearly 12,000-word transcript represents more than 85 percent of the original interview.  

The editors, both in 2013 and 2017, have also at times added brief text in brackets to the transcripts (full names, acronyms, clarity completion of sentences) to help clarify certain points. In addition, we inserted brief footnotes to provide additional historical/biographical information on individuals, events or acronyms mentioned.

Finding Ya’tza

I knew Ya’tza’s name long before I met him.  Since my early research for Israel and the Bomb, in the  early 1990s, I was aware of the role Ya’tza played as chief liaison between the Israeli Defense Force (IDF) and the nation’s nuclear program. Ya’tza was high on my list of “persons of interest” I wanted to interview, but it was not until early summer 1999 that I learned by chance Ya’tza was living in New York City. When I finally got in touch with him, I was pleased to learn he knew who I was, and more pleased when he invited me for a visit at his mid-town apartment. 

At the door I saw a white-bearded, seventy-five year old Palmachnik — a friendly, talkative Israeli, with a distinct, rugged Hebrew voice. As we started the conversation, I started to feel as if he had been waiting for my call.  Not only was he familiar with my work, but I got a sense that it had helped trigger his memory. At one point, he was lecturing me on ignoring the IDF perspective.  It felt like he was asking me, “How could you have written this book without first talking to me?” Ya’tza gave me a printout of his unpublished fictional manuscript, Atomic Incident, which I began reading immediately on the train back to Washington, D.C. After that initial meeting, I travelled to New York several more times just to hear his story in more detail. 

May 1967:  A Crash Nuclear Activity

In mid-May 1967, nobody in the Israeli army anticipated a war anytime soon. Ya’tza was at that time on a professional tour in the United States, visiting the headquarters of the Rand Corporation in Santa Monica, California.  Ya’tza was then a colonel, the head of Weapons Means Department (AMLACH) at the IDF general staff; effectively Ya’tza served as the IDF chief weapons technology officer. 

On May 14, 1967, however, the Egyptian army started moving into the Sinai, and two days later Egypt requested the United Nations Emergency Force (UNEF) commander to withdraw his forces from their observation posts along the Israeli-Egyptian border. Following an exchange of confusing messages between New York and Cairo, Egypt requested complete withdrawal of the UNEF.  Soon after, Ya’tza received a message from his boss, General Ezer Weizman, the IDF Chief of Operations, to drop everything and fly back home.  And so he did.

Ya’tza arrived in Israel around May 20, and found the IDF general staff in a state of crisis.  Almost overnight, war with Egypt had become a serious possibility. Ya’tza worried about the Egyptian surface-to-surface missiles, in particular the possibility of a strike on Tel Aviv, maybe even with chemical warheads.  The Egyptian missile project was something Ya’tza had followed for some time; Egypt had deployed and used chemical weapons against civilians in the war in Yemen only two years earlier. While the Israeli Military Intelligence (AMAN) discounted the Egyptian missile issue, though not the gas issue – some viewed the Egyptian missile project a fake project – Ya’tza took it seriously.    

Upon arrival, Ya’tza met Weizman’s deputy, General Rechavam “Gandi” Ze’evy, who ordered him to “Prepare everything you got.”  That meant, practically speaking, elevating the readiness of the entire R&D program under Ya’tza’s supervision.  Every piece of hardware being worked on should be rendered usable.  This order initiated what would be called the “Shimshon Operation.”

In following this order, Ya’tza learned from one of his lieutenants at AMLACH that the people of the nuclear project were working around the clock to complete and make “usable” an explosive nuclear device.  This device was an experimental nuclear explosive system, something akin to the nuclear “gadget” the United States had tested in Alamogordo, New Mexico, on July 19, 1945 (codenamed “Trinity test”); it was not an actual bomb that could be placed on a missile or dropped from an airplane.

The crash effort to produce the nation’s first nuclear device took place at different sites and through separate groups. In the north, RAFAEL engineers and scientists, headed by Yevgeny “Jenka” Ratner, were building the explosive system, commonly called “the spider”; in central Israel at Dimona, and elsewhere, nuclear teams were working on assembling the first complete nuclear core.  The man in charge of all this crash activity was the director general of Israeli Atomic Nuclear Energy, and the head of the new Scientific Administration, Professor Israel Dostrovsky.

As the chief military liaison with the nuclear project, Ya’tza knew the nuclear project was making good headway on an experimental device, but now he was updated about the rush to prepare a usable device as quickly as possible. Ya’tza did not know – or did not remember – the exact circumstances that led to the decision to sprint to complete the device, but he saw it as “the most natural desire of weapons developers” in such a situation. It is only “logical,” Ya’tza said, that the people at the top of the nuclear project would like to hand the prime minister another option, a very different option, just in case everything else failed. For the project leaders, the crisis was a unique opportunity to demonstrate their importance to the prime minister, to provide him with a unique option, a “doomsday option.”  It also must have boosted the morale of all those involved, including the prime minister, himself.[ii]

Ya’tza immediately recognized that the crash activity on the device lacked an operational dimension.  Only the IDF could provide the resources – human and material – to make this technical capability truly operational, to create the operational structure for a demonstration.  Ya’tza emphasized during our conversations that nobody at the IDF or at the nuclear project asked him to draft an operational order, but rather he took it upon himself to transform the newly formed technical capability, and the idea of conducting a demonstration, into a viable military operation.    

The unexpected existential crisis that Israel suddenly faced pushed the nuclear project to uncharted territories.  The desire to provide the prime minister some sort of nuclear option revealed all sorts of problems that until then had never been considered.  For example, in May 1967, there were no well-defined lines of communication or authorities, let alone procedures and protocols, to connect the military with the nuclear project.  Nobody thought seriously about such issues before because it was so premature, too embryonic. But when a device was about to be produced and was required to be “usable,” those new issues needed to be addressed.


Ya’tza believed it was he – as the IDF liaison – who initiated and promoted a role for the IDF in that crash effort,  and transformed the idea from a demonstrative capability into something operational. Ya’tza stressed that there was little order in this spontaneous initiative. It was highly improvised and there were no well-defined lines of communication between the IDF and the nuclear project.  The fluid nature of the situation allowed him to propose a military-operational dimension to that crash activity. In consultation with the head of the nuclear project, Dostrovsky, and with approval from his superiors, Ze’evy and Weizman, Ya’tza drafted an order creating a logistical and command framework for a demonstration test. The operation was codenamed “Shimshon” [Samson], a clear reference to the Samson story from the book of Judges in the Bible.

As Ya’tza recalled, the original Shimshon order he drafted was a two or three-page document plus some appendices stating in a standard military style the operation’s objective, intention, means and methods of execution, as well as determining the size of the military force required to execute the operation.  Ya’tza stressed that the order was meant only for preparations, not execution.

The order established a small, ad-hoc IDF team with the necessary skills for such an operation: combat and security, communication, medics, etc. This was somewhat out of the ordinary because it required the IDF to support non-military personnel; the nuclear device was not considered an IDF asset – let alone a weapon – nor was it “owned” by the IDF.  The role of the military team was to support the civilian nuclear team: to secure the area and to establish secured communication with the prime minister’s office.  Ya’tza believed the order named him as the military commander of the operation; Dovik Tamari, from the elite Sayeret Matkal, was named as his deputy in that operation. 

As noted, the operation also included a civilian team that consisted of key members from the nuclear project – scientists, technicians and other support personnel – headed by Israel Dostrovsky, the nuclear project chief.  Their mission was to transport the “spider,” the semi assembled device, along with the nuclear core, to the target site, to “marry” the “spider” with its nuclear core, to connect ignition wires to the command post, and to wait for an order from the prime minister. 

According to the plan, the operation team would transported to the target site in two Air Force Super Frelon helicopters – the largest helicopter in Israel’s fleet – each capable of carrying a maximum of 38 people.  One helicopter would carry the military group, the second the civilian, nuclear group.  The military team was set to meet in the old police station in Gedera, in central Israel; the nuclear group would organize elsewhere in central Israel, where the core and the “spider” would have arrived separately from different locations.      

The selected landing site was a mountain in eastern Sinai, roughly 20 kilometers from the large Egyptian military complex in Abu Ageila.  The proposed ground zero was near the landing spot and a command hideout post would have been dug in a canyon or a creek about a kilometer and a half from the landing point.  It was evident that a nuclear flash arising from that location would be visible for many tens kilometers throughout the Sinai and the Negev.

According to the plan, a small paratroop force would have diverted the attention of the Egyptian army in the area to allow the team to prepare the nuclear demonstration upon an order from both the prime minister and the chief of staff.  That meant preparing the device at ground zero, itself, establishing an electrical system to activate the device from the command post, and setting up secure communication between the command post and the prime minister and chief of staff.

Rabin’s Signature and Preparations

After drafting the “Shimshon” plan, Ya’tza brought it to his superior at AGAM, General Ze’evy for approval. According to Yatza, Ezer Weizman was aware of the activity but left it entirely to Ze’evy, as he was too busy on other things. Ze’evy made a few editorial changes in the text and approved it.  Then they went to present the order to Chief of Staff Yitzhak Rabin for his approval and signature. 

Ya’tza recalled that they met Rabin soon after his two-day medical absence on May 23-24 – what is now known as Rabin’s mental breakdown, a period of 36-48 hours in which Weizman served as the acting chief of staff.  This suggests the meeting most likely took place sometime between May 26 and May 28.  According to Ya’tza, Rabin did not look good.  Rabin’s office was unusually quiet and dark, all the curtains were drawn, and Rabin was sitting alone. They showed him the document, but Rabin seemed unable to focus. He read the document but hardly asked any questions. He signed and the two left.  Ya’tza remembered thinking to himself it was a very odd meeting, given the fact Rabin just authorized initiating steps towards a nuclear demonstration.[iii] Ya’tza also noted that the entire process of producing and approving the order was rather fast; it may have taken no more than half a day.  

Equipped with formal authority, Ya’tza started to form the team. He met with Lt. Colonel Dovik Tamari, the former SayeretMatkal commander who Ze’evy had named as Ya’tza’s deputy.  Together they visited the R&D installation in northern Israel where the device was built, and met key people involved in the effort. Ya’tza recalls Tamari taking extensive notes.   

The highlight of the preparations was a reconnaissance flight by helicopter over the selected landing site in eastern Sinai, not too far from the Israeli border. They flew a Super Ferlon, the same type of helicopter assigned for the operation. Ya’tza vividly recalled among the people on board Dostrovsky, “always with his short pants,” and Tamari; there may have been a few others on board: Ze’evy, Dan Tolkovsky, a former commander of the Israeli Air Force and a member of the Israeli nuclear priesthood, Moshe Shachar and some air force officers.  The flight took off from Tel Nof Air Force Base and crossed the Egyptian border into the Sinai at low altitude. But just as the helicopter approached the landing site, the pilots received a message from ground control that Egyptian jets were taking off, and they turned around. “We got very close to Abu-Ageila, we saw the mountain, and we saw that there is a place to hide there, in some canyon …” Ya’tza recounted.

While preparing for Shimshon, Ya’tza told me more than thirty years later, all sort of qualms crossed his mind: Would it explode?  Would he survive the blast, heat and the radiation of the explosion?  What would it be like to be burned up in such an explosion?  “Even if we could have done it,” Yatza told me at one point, “I probably would have been killed.” Ya’tza also had qualms about Israel being the second state in history to conduct a nuclear explosion in a war.  How would the world react if Israel would be the second nation to explode a nuclear device during war?

The Arrival of Dayan and Tzur

On June 1, 1967, Prime Minister Eshkol relinquished his Defense portfolio and former chief of staff, Moshe Dayan, was appointed Israel’s new Minister of Defense.  In anticipation of war, Eshkol asked Minister Without Portfolio Israel Galili and former Chief of Staff Yigal Yadin to draft a short document defining and dividing the authorities and responsibilities between the prime minister and the minister of defense.  The first paragraph specified the military actions that could not be taken without prior approval of the prime minister.  Among those prohibitions was the use of unconventional weapons, the only implicit reference to the nuclear issue.[iv]

Within hours, the newly appointed Minister of Defense Dayan stripped Deputy Minister of Defense Zevi Dinstein of his authorities at the ministry, including his role as the nuclear project’s overseer. Dayan appointed former chief of staff Tzvi Tzur (Chera) as his chief civilian aide and as Dinstein’s replacement at the ministry.  That made Tzur the new overseer of the nuclear project, and the de facto head of the newly created nuclear administration system.[v]  By June 2, Israel Dostrovsky had essentially two supervisors: Tzur (on behalf of Minister of Defense Dayan) as his immediate supervisor and Prime Minister Eshkol as his ultimate boss.[vi]

These changes had an impact on Shimshon. Upon assuming his new post, Tzur took charge and reviewed every aspect of the operation. With a reputation as an exceptional administrator, Tzur infused order and clarity into what had until then looked pure improvisation.  During our interview, Ya’tza praised Tzur’s role as the new overall boss of the nuclear project. In the few remaining days before the war Tzur held daily coordination meetings with the civilian and military key figures involved, including Dostrovsky, Ya’tza and a few others. According to Ya’tza, it is not that Tzur changed much in what was going on, but rather he called attention to many loose ends and gaps between the various players and agencies involved. 

The War and Afterwards

On June 5, 1967, the first day of the Six-Day War, Ya’tza and his deputy, Dovik Tamari, were on full alert in Ya’tza’s AMLACH office at IDF headquarters.  They awaited the command to activate Shimshon.  Ya’tza  said that even up through that morning he still believed Shimshon could be mobilized. 

But by late morning, when it became known that the Israeli Air Force destroyed most of the Egyptian Air Force on the ground, it became clear that Shimshon would remain just an idea, a worst-case scenario. The commanding team was dismantled the next day.      

A few days later, after the war was over and everyone in Israel was celebrating, there was a final meeting put together by Tzur to review Shimshon.  They discussed lessons learned and what should be done next--how to bring the nuclear project back to its routine, given what was learned from this emergency exercise.  Ya’tza had another creative idea.  The night before the meeting, he wrote a memo to Tzur proposing to conduct a test anyway.  His reasoning in the memo was though the Arabs may be defeated; they were not ready to negotiate a peace. Israel should take advantage of this rare victory; it can now can do whatever it wants. This is the time to test and declare capability, for both political and technological reasons. 

Ya’tza’s proposal was totally dismissed; Tzur never even raised it for discussion.  No one else referred to it.  The consensus was to bring the nuclear project back to its secretive routine as if nothing happened.  As Tzur noted in the interview he gave to the Rabin Center more than thirty years later – which is part of this special collection -- he viewed the whole effort as a mere technical status check.  Politically, he thought a nuclear demonstration made no sense, “It would have destroyed what we already had.”  Technologically, he viewed it as an amateurish improvisation.


For more than three decades, few people had any idea of the nuclear drama that took place in Israel on the eve of the 1967 War.  Even the handful who did hardly ever talked about it, even in private.  “Shimshon” fell into oblivion, even for those who knew. It was as if it never happened, another casualty of the Israeli nuclear taboo.

For Ya’tza, however, never forgot those events.  The memory lay dormant for decades, but gradually it came back to life.  When I met Ya’tza in the summer of 1999, he considered Shimshon one of the two most remarkable events of his life; the other was the fall of Gush Etzion in the 1948 war. He started referring to Shimshon as “my legacy.”

Listening to Ya’tza’s recollections made me reflect on the nature of memory, narrative and history, and the relationship among them.  Long-term memory seems to be made of narrative anchored in distinct and vivid moments – events, situations, encounters. People vividly recall these individual moments, but the narrative is larger than the sum of those moments and it always has blanks, holes and sheer fog. Often, we fill these with guesses disguised as memory.  True memory is inescapably fragile.

Ya’atza and I talked much about the fragility of human memory. It was clear that while some moments he recalled vividly, others he hardly remembered.  He was aware that his narrative of events was at certain points more conjecture than memory.  He conceded having doubts about some of his claims. Realizing the difficulty in uncovering the past, my job was often to challenge him by raising issues, puzzles, inconsistencies with his narrative and forcing him either to provide explanations or to admit memory lapses. The interview sometimes sounds more like an interrogation. At times Ya’tza tried to address those difficulties by digging deeper into his memory and at times by proposing or reconstructing logical explanations. Often it was truly difficult to reconstruct what happened.

The fragility of memory is inescapable in any kind of oral history, and certainly it was a challenge here. 


[i] Israel Dostrovsky (1918-2010), an Israeli physical chemist who was a prominent scientist in the Israeli nuclear program.  He founded HEMED GIMMEL in 1948, was among the founding members of the Israeli Atomic Energy Commission (IAEC), served as the first director-general (1966-71), the fifth president of the Weizmann Institute of Science, laureate of the 1995 Israel Prize in the physical sciences.  See Avner Cohen, “Last of the Nuclear Mohicans,” Ha’aretz, October 29, 2010.

[ii]  Indeed, in his briefing to the Committee on Foreign Affairs and Defense of the Knesset on May 26 Prime Minister Eshkol hinted about this extraordinary activity.  See those minutes in this collection.

[iii] Ya’tza told me that he considered the Shimshon operation order the most important military document he had ever drafted during his entire IDF service. For this reason, he kept a copy of the document in his safe at his home.  After he left Israel in the early 1980s his ex-wife arranged that the document was removed by security. Months later, upon visit, Ya’tza was summoned and reprimanded by keeping for keeping the document.  Decades later, as Ya’tza got haunted by his old 1967 memory, he reconstructed the order in his fictional Atomic Incident.

[iv] Avner Cohen, The Worst-Kept Secret: Israel’s Bargain with the Bomb (New York: Columbia University Press, 2010), pp. 175.   

[v] On the creation of the nuclear administration in 1966, formally referred to the Scientific Administration, the minhal, see Avner Cohen, Israel and the Bomb, pp. 228-31; also, The Worst-Kept Secret: Israel’s Bargain with the Bomb, pp. 172-4.

[vi] Although Eshkol as the prime minister remained formally in control of the nuclear project, in practical managerial terms, the newly appointed minister of defense, Dayan, controlled the nuclear bureaucracy, the minahl.  During Eshkol’s tenure at the Ministry of Defense this authority was practically passed on to Dinstein who served as Eshkol’s ears and eyes on the secret project.  By June 2 all Dinstein’s responsibilities were given by Dayan to Tzur.  Avner Cohen, The Worst-Kept Secret: Israel’s Bargain with the Bomb, pp. 174-75.