What is Dimona? Inside Israel’s ‘secretive’ nuclear facility that FOOLED US intelligence for years

After 12 days of the Israel-Iran war, during which the US struck Iranian nuclear sites using B-2 bombers and bunker busters, an American-brokered ceasefire appears to be holding, for now. The conflict began after Israel launched surprise strikes on Iran, calling them a “pre-emptive measure” to prevent Tehran from developing an atomic bomb.

Tel Aviv's campaign to stop Iran from making nuclear weapons has brought attention to Israel's own nuclear programme. One key location is the Dimona nuclear facility, a site shrouded in secrecy and long regarded as the crown jewel of Israel’s nuclear programme.

What exactly is Dimona?

The Dimona nuclear facility, located in southern Israel, is the country’s most sensitive and highly classified nuclear site. Built in 1958 with French assistance, it has long been associated with Israel’s undeclared nuclear weapons programme.

What makes Dimona unique is that even the US intelligence community failed to detect its purpose for years. The site remained under wraps until December 1960, when a University of Michigan professor named Henry Gomberg uncovered the truth.

How was Dimona discovered?

While visiting Israel as a consultant to the Israeli Atomic Energy Commission, Gomberg observed signs of a much larger project than the one publicly shown at Soreq. He reported his findings to the US Ambassador in Tel Aviv and the Atomic Energy Commission in Paris. Upon returning to Washington, he briefed US officials, leading to the CIA confirming Dimona’s existence.

On 7 December 1960, the US State Department summoned the Israeli ambassador for an explanation, and Dimona was formally added to the diplomatic agenda. A post-mortem report was later sent to President Kennedy, analysing why the US had failed to detect the site earlier. From Israel’s point of view, the late discovery was a stroke of luck, giving the project time to advance without interference.

Is Dimona still active today?

According to a June 2024 SIPRI report, Israel is modernising its nuclear weapons systems, including upgrading production facilities likely near Dimona. Though Israel has never confirmed it has nuclear weapons, international experts estimate the country holds about 90 nuclear warheads. SIPRI also reported signs that Israel was upgrading the reactor in the Dimona region, as part of a broader modernisation effort.

What role does Dimona play in Israel’s nuclear strategy?

Israel has followed a long-standing policy of “nuclear ambiguity”, refusing to confirm or deny its nuclear arsenal. It insists it will not be the first to introduce nuclear weapons into the region. However, hints over the years, including historic discussions during the 1973 Yom Kippur War, suggest the existence of a functional deterrent. In recent years, public statements by far-right politicians have further revived speculation. In November 2023, Israeli Heritage Minister Amichai Eliyahu suggested dropping a nuclear bomb on Gaza.