Revealed: Britain secretly believes Israel has nuclear weapons, but won’t admit it

Declassified files show Whitehall has long assessed Israel as having an atomic arsenal, contrary to what ministers tell parliament.

19 April 2023

The Dimona reactor, where Israel is widely suspected of developing nuclear weapons. (Photo: Thomas Coex / AFP via Getty)

  • UK military official feared that “openly admitting” knowledge of Israeli nuclear arms would “create pressure for action against Israel”.
  • Israelis were described as “probably the world’s greatest proliferators” by British diplomat who went on to head the Foreign Office
  • UK diplomats secretly agreed with Seymour Hersh’s 1991 book on Israel’s nuclear capability
  • Revelations contradict what current foreign secretary James Cleverly recently told parliament.

British officials have privately regarded Israel as a nuclear-armed power for at least 40 years, while telling the public they cannot make an assessment.

Israel has never formally declared it has a nuclear weapons programme, a position UK ministers do not publicly contradict.

But behind the scenes in Whitehall, staff in the Foreign Office and Ministry of Defence (MoD) have long believed Israel has developed nuclear arms.

The revelations are contained in files released to the UK National Archives as recently as last year and found exclusively by Declassified UK.

They severely undermine statements made to parliament by successive government ministers including the current foreign secretary, James Cleverly.

He told MPs last February how “Israel has never declared a nuclear weapons programme” and insisted the UK government was encouraging Tel Aviv to sign the non-proliferation treaty as a “Non-Nuclear Weapon State”.

However, a file from 1983 and marked “secret” shows the MoD believed Israel “probably produces enough plutonium for one nuclear weapon per year.” It added: “Thus she may now have a stock of about twenty,” having gone into production in 1964.

A group of British military officers were then told in 1985 by Israeli defence minister (and former PM) Yitzhak Rabin that: “Israel will not be the first to introduce nuclear weapons, but she will keep the option in case the Arabs get the bomb”.

A British diplomat in Tel Aviv, Tim Dowse, regarded the second part of Rabin’s comment to be “as close as we are ever likely to come to an explicit confirmation that Israel has a nuclear capability.”


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Hersh was right

The issue resurfaced in the early nineties after US investigative journalist Seymour Hersh published a book The Samson Option, which contained new evidence about the alleged scale of Israel’s nuclear programme.

Although Hersh has faced an establishment backlash over his most recent claims about the US bombing the Nord Stream 2 pipeline, British officials took his research on Israel’s nuclear programme seriously.

His book prompted questions in 1992-3 from a Labour peer, Lord Kennet, about whether Whitehall agreed with Hersh’s claim that Israel had nuclear weapons.

An official from the MoD nuclear policy department, David G. Johnson, privately told colleagues: “Although we believe there is such a programme, the fact remains that we do not have firm evidence for this.” 

The first part of that statement was kept from Kennet, and Conservative defence minister Arthur Gore simply told the peer: “We have no firm evidence either to confirm or to deny that Israel may have a nuclear weapons programme.”

On seeing that answer, Foreign Office staffer Peter Spoor commented privately: “Strictly speaking this is true, since we have no direct evidence. But it is slightly disingenuous; there is a wealth of circumstantial evidence in the public domain and we work on the assumption that Israel has a nuclear capability.”

The MoD official, David Johnson, feared that “openly admitting our suspicions…would do more to undermine the credibility of the nuclear Non-Proliferation Treaty than does the current ambiguity surrounding the status of Israel’s nuclear programme.” 

Johnson added: “It would also create pressure for action against Israel which would be difficult to satisfy”.

Spoor worried similarly that “the inability of the international community to agree on an effective response would raise a political storm and help legitimise proliferation by other states.”

Under the Nuclear Non-Proliferation Treaty of 1970, countries without nuclear weapons agreed to avoid acquiring them. 

Israel is one of only three countries never to have signed the treaty, despite its programme being an open secret.

The Stockholm International Peace Research Institute (SIPRI) estimates Israel now has 90 nuclear warheads and is “believed to be modernizing its nuclear arsenal”.


Britain’s nuclear arsenal


‘World’s greatest proliferators’

By 1993, a colleague of Spoor’s in the Foreign Office’s non-proliferation and defence department (NPDD) had made an even more stark internal assessment. Peter January wrote: “We have no hard evidence but we believe that Israel possesses nuclear weapons”. 

His boss, the NPDD’s assistant head, Simon Fraser, said the Israelis “are, after all, probably the world’s greatest proliferators, and I think we need to maintain a fairly crisp tone of voice with them.” 

Fraser went on to run the Foreign Office from 2010-15.

A British diplomat in Tel Aviv, Andrew Pearce, tried to strike a softer note, saying: “Israel is almost certainly a nuclear weapons possessor, but I would hazard a guess that she would be one of the last countries in the world to pass nuclear secrets or technology to those countries with current nuclear ambitions (e.g. the Iranians, Iraqis etc) i.e. to proliferate as opposed to possessing herself.”

His argument received short shrift from colleagues in the arms control division. David Gordon-MacLeod sought to “re-emphasise at the outset that NPDD employs the acquisitive/possessive concept of proliferation. On this basis therefore Israel remains a proliferator.”

Ten years later, the UK would illegally invade Iraq based on fabricated intelligence that Saddam Hussein possessed weapons of mass destruction. 

Israel, meanwhile, has become one of Britain’s closest allies in the Middle East – despite its increasingly far-right government.

Both London and Tel Aviv regularly denounce Iran’s alleged attempts to obtain nuclear weapons, and British ministers have unequivocally said: “Iran must never develop a nuclear weapon”. 

Israel is even suspected of assassinating the head of Iran’s nuclear programme.

The UK government’s refusal to publicly acknowledge Israel as a nuclear state is one of the ways Whitehall shields Tel Aviv from international criticism.

Reacting to our findings, Alicia Sanders-Zakre, a spokesperson for the International Campaign to Abolish Nuclear Weapons, commented: “Israel, alongside the other eight nuclear-armed states retains a capability to commit mass atrocity – indiscriminately slaughtering hundreds of thousands if not millions of people with weapons of mass destruction.

“Israel must take immediate steps to eliminate its nuclear arsenal, including by joining the Treaty on the Prohibition of Nuclear Weapons.”

Read the documents we found below