Fifty U.S. documents from the early 1960s were declassified by the U.S. National Security Archive on Thursday, shedding light on Israel’s attempts to hide one of its best-kept secrets to this day: details on its nuclear program. The Americans ultimately believed the Israelis were providing “untruthful cover” about intentions to build a bomb.

The documents include papers from the White House, the State Department, the Atomic Energy Commission and U.S. intelligence agencies. The editors are Avner Cohen, a professor at the Middlebury Institute of International Studies at Monterey, and William Burr, the head of nuclear affairs documentation at the National Security Archive, which is based at George Washington University in the capital.

One document provides the minutes of a meeting between U.S. President John F. Kennedy and Prime Minister David Ben-Gurion on May 30,1961, at the Waldorf Astoria in New York.

Cohen and Burr call that meeting a “nuclear conference” – Israel’s nuclear program greatly concerned Kennedy. When he met his predecessor Dwight D. Eisenhower before the changeover of January 20, 1961, he was quick to ask which countries Ike believed were determined to obtain nuclear weapons.

Open gallery view A partial view of Israel's Dimona nuclear power plant in the southern Negev desert. Credit: AFP

Secretary of State Christian Herter replied: “India and Israel,” before recommending that Kennedy pressure Israel into agreeing to have its nuclear facilities inspected.

According to the details of that meeting, already published in the past, Ben-Gurion told Kennedy that Israel's Dimona project was peaceful. The American transcript says: “Our main – and for the time being only – purpose is [cheap energy]. We do not know what will happen in the future.”

The Israeli transcript says: “For the time being, the only purposes are for peace but we will see what happens in the Middle East. It does not depend on us.”

In the newly released minutes, the Americans said “Ben-Gurion spoke rapidly and in a low voice so that some words were missed.” Kennedy had a hard time asking concrete questions.

Open gallery view U.S. President John F. Kennedy and Israeli Prime Minister David Ben-Gurion. Credit: NY Daily News via Getty Images

“Ben-Gurion mumbled and spoke very softly. It was hard to hear him and understand what he was saying, partly due to his accent,” Cohen, author of “Israel and the Bomb," told Haaretz.

“It seemed he was leaving in certain ambiguities, consciously or otherwise, so it couldn’t be said he totally lied to the president. As a result, the president couldn’t ask for clarifications, as noted in the minutes. We only discovered this now, with the declassification of the minutes.”

The minutes also reveal that the person taking notes, Assistant Secretary of State Phillips Talbot, thought he heard Ben-Gurion mention a “pilot plant for plutonium separation, which is needed for atomic power.” Talbot also heard Ben-Gurion say this might happen “three or four years later.” He understood the prime minister as saying Israel had no intention to develop nuclear weapons for the time being.

“Ben-Gurion, in what he said and in what he didn’t, was hinting that the nuclear reactor in Dimona could have military potential in the distant future, or at least that is what Talbot believed he heard,” write Cohen and Burr in their explanatory notes to the documents.

Much more plutonium than was known

Ten days before that meeting, another key meeting took place. This was the first visit by American inspectors (as the Americans called them – Israel called them visitors) at the Dimona reactor. The Israelis considered the visit productive. The inspectors believed the facility was under construction and consistent with the Israelis’ description: a research reactor for peaceful purposes.

The complete report on the U.S. Atomic Energy Commission’s visit is part of the new batch of declassified documents. According to the report, people at Dimona told the Americans that the reactor’s output would probably be doubled in the near future.

“This could have served as a warning signal and a worrying indicator that the reactor was capable of producing much more plutonium than was known at the time,” Cohen and Burr say in the explanatory notes. In fact, the visitors returned home satisfied, and their positive report paved the way for the Kennedy-Ben-Gurion meeting.

Another interesting document is the CIA’s National Intelligence Estimate on Israel crafted in October 1961, a few months after the Kennedy-Ben-Gurion meeting. This is the only declassified document published without deletions. It was released a year ago but overlooked by researchers.

“There are some very interesting lines there showing what the U.S. intelligence community really thought about Dimona,” Cohen says.

The document reveals that at the end of 1961, Washington believed that the reactor’s unambiguous purpose was to create an infrastructure for nuclear weapons.

“The Israelis intend at least to put themselves in the position of being able to produce nuclear weapons fairly soon after a decision to do so,” the Americans said. They expected the Israelis to have enough nuclear material for two bombs by 1965 or 1966.

“The significance of this is that the Americans knew that Ben-Gurion was misleading them,” Cohen says. “They couldn’t or wouldn’t directly accuse him of lying. Maybe they didn’t want to disclose what they knew. It’s clear the intelligence community knew that what Ben-Gurion said and what the inspectors saw in Dimona were far from being the whole truth.”

According to the explanatory notes: “The bottom line is that in 1961 the CIA already knew or understood that the way Israel referred to Dimona, whether through Ben-Gurion or through its scientists, was an untruthful cover.”

Along with Ben-Gurion’s silences and fuzzy details, the documents show that the Americans wondered whether the Israelis were deliberately trying to deceive them; for example, during a second visit to the reactor in September 1962.

One document, dated December 27, 1962, wonders about Israel’s unconventional hospitality. Inspectors arrived at the Nahal Soreq reactor for a routine visit in September. The scientific director there was Yuval Ne’eman, later president of Tel Aviv University and science minister for Menachem Begin.

The runaround, Israel-style

The Americans had pressured Israel to allow a second visit to Dimona, Cohen says.

The documents show that Ne’eman decided to take his guests to the Dead Sea. On the way back, as they were passing the Dimona facility, he suggested an unplanned visit.

According to the documents, Ne’eman said he could organize a talk with the facility’s director, and the two inspectors agreed. But it turned out the director wasn’t there, so senior engineers organized a 40-minute tour, much shorter than what was called for by protocol.

Following the tour, the Israelis suggested that the Americans return the following day, but the Americans wondered whether this was a diversion. After all, the Israelis knew the Americans were due to fly home the next day. The next available flight was four days later.

The documents show that the inspectors were puzzled, not knowing whether their visit was part of the inspection or whether they were only day trippers. Either way, the visit was incomplete and did not include visits to all buildings and inspections of all installations.

Ultimately, Israel got what it wanted. The inspectors were duly impressed and their report described Dimona as a reactor for research purposes, not for plutonium production.

Still, CIA officials who later discussed the visit cast doubt on the genuineness of the rapid-fire visit. “They were very uncomfortable with it. It seemed like a trick to them,” Cohen said.

“The documents show that a senior CIA officer said basic intelligence requirements had not been fulfilled and there were inconsistencies between the results of the first and second visits in terms of the use attributed to some of the equipment.”

The documents also show that Washington wanted to impose security surveillance on Prof. Israel Dostrovsky, a guest researcher in the United States at the time. Dostrovsky was a founder of Israel’s nuclear program and later the first head of the Israel Atomic Energy Commission, as well as the president of the Weizmann Institute of Science and a 1995 Israel Prize winner.

In 1961, the State Department asked the relevant agencies to keep an eye on Dostrovsky while he was working at the Brookhaven National Laboratory on Long Island. This was seen as a preventive measure designed to protect U.S. nuclear expertise. Dostrovsky died in 2010.

The U.S. National Security Archive’s website contains other U.S. documents on Israel’s nuclear program. One can learn there about the background for the 1969 meeting between President Richard Nixon and Prime Minister Golda Meir, where the ambiguity doctrine was born as a binational policy.

“Despite the official ambiguity policy of Israeli governments, meaning that no factual information about Dimona is ever divulged, there’s abundant historical information on Dimona and the history of Israel’s nuclear program – one of the most studied projects in academic studies on nuclear programs,” Cohen says.