A leading Washington think tank has detailed what it says was a secret Israeli plan to detonate an atomic bomb in the event it faced defeat in the 1967 Mideast war.

The operation never took off. But details about the doomsday scenario, in which Israel planned to set off a nuclear weapon atop a remote mountain in the Sinai Peninsula, shed new light on the fearful climate at the time. It also could undermine Israel’s decades-long policy of nuclear ambiguity.

The Nuclear Proliferation International History Project of the Woodrow Wilson International Center for Scholars unveiled a website Monday devoted to “Operation Shimshon,” the codename for what it said was the hastily arranged plan.

Israel’s Foreign Ministry had no comment.

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