The Hamas attack on 7 October 2023, was the greatest disaster in the history of the State of Israel and the deadliest massacre of Jews since the Holocaust. During the attack, 1,163 Israelis and foreigners—almost all civilians—were murdered, nearly 2,000 were wounded, and a further 251 were abducted to the Gaza Strip. Severe acts of rape and abuse were also committed during the massacre.

The magnitude of the attack and the damage it caused were primarily the result of an intelligence-warning failure by the Israeli intelligence community. Such failures are not uncommon. On the contrary, in every case since 1939, when an initiating party sought to achieve surprise at the outbreak of war, it succeeded. The most notable examples are Operation Barbarossa, the German surprise attack on the Soviet Union in June 1941; the attack on the United States at Pearl Harbor six months later; and the Egyptian-Syrian surprise attack on Israel on Yom Kippur in October 1973.

Nevertheless, the warning failure on 7 October was uniquely complete—a full-spectrum failure produced by the Israeli intelligence community’s belief that Hamas had been successfully deterred from confronting the IDF. Even if Hamas wanted to attack Israel, the intelligence community was confident that the terror group lacked the capabilities to carry out a large-scale attack like the one that occurred that morning.

Such a failure is unprecedented, and it was especially remarkable because it occurred in a professional, high-quality, and highly successful intelligence community such as Israel’s. To explain the roots of that failure, I want to examine the most recent information available and compare it to the three 20th-century surprise attacks mentioned above—Operation Barbarossa, Pearl Harbor, and the Yom Kippur War.

Three Preconceptions

At the root of the 7 October warning failure were three fundamental preconceptions.