In the months and weeks leading up to the 1973 Arab-Israeli war, Israeli intelligence had ample evidence—from a highly placed source in Egypt, to visual data, to warnings from the king of Jordan himself—that Cairo and Damascus were planning to attack. Yet its leaders chose to ignore the warnings, thus finding themselves caught dangerously off guard. Bruce Riedel, whose work for the CIA brought him into close contact with key players in the story, seeks to understand what went wrong, and argues that Jerusalem made similar mistakes in the First Lebanon War.

Israeli intelligence failed to see war coming in 1973 because it was wedded to a concept . . . that the Arabs would not go to war because they would lose, therefore the danger of war was minimal. All indicators of war preparations and any warnings of war were fed into the concept and then explained away. But the concept was not just an intelligence concept, it was a policy concept that the Israeli political leadership at the top deeply believed.

But more than the concept was in error. The Israeli intelligence community and the Israeli policy community had created a small and intimate feedback loop in which their common assumptions about the enemy were never challenged. Moshe Dayan, a military hero of epic proportions, shared the fundamental assumption that the Arabs were incompetent with his intelligence advisers. Since then-Prime Minister Golda Meir relied on her generals entirely on military issues, she shared it as well. . . . The Americans proved to be no help, either. They too were mesmerized by the [Israeli] concept. . . .

The Agranat Commission, [formed by the Knesset to investigate the failures of the Yom Kippur War], recommended some organizational changes to prevent another disaster. This is always the default position of bureaucracies when intelligence fails: change the organizational flow chart, not the menu itself. . . . The theory was that having three organizations each independently study the data [produced by intelligence] and make estimates would diminish the chance of the concept going unchallenged. . . .

In Lebanon in 1982, the Israeli intelligence community relied heavily on its Christian ally, the Lebanese Forces [or Phalange], for intelligence about the complexities of Lebanese politics. For decades, Israel’s concern in Lebanon had been the Palestinian terrorist organizations and the Syrian occupation army, while Lebanese politics and society were not a priority. For understanding this arena, the Israelis turned to the Lebanese Forces.

Overreliance on the Christians led Israeli analysts and policymakers to create a new concept, Riedel argues, that proved equally flawed:

[T]he bureaucratic solution of the Agranat Commission—creating a rival analytic service to the [IDF’s intelligence wing]—failed in Lebanon because the [military-intelligence analysts] would not challenge the “concept” and warn that the Phalangist viewpoint was flawed. . . . [T]he “concept” of Christian primacy in Lebanon failed to recognize the nascent power of the Shiite community and its capacity to create a strong insurgency against the IDF occupation of half the country. In particular, the military intelligence and the Mossad were very slow to recognize the rise of Hizballah.

On Tuesday, a Hizballah drone attack injured three people in northern Israel. The next day, another attack, targeting an IDF base, injured eighteen people, six of them seriously, in Arab al-Amshe, also in the north. This second attack involved the simultaneous use of drones carrying explosives and guided antitank missiles. In both cases, the defensive systems that performed so successfully last weekend failed to stop the drones and missiles. Ron Ben-Yishai has a straightforward explanation as to why: the Lebanon-backed terrorist group is getting better at evading Israel defenses. He explains the three basis systems used to pilot these unmanned aircraft, and their practical effects:

These systems allow drones to act similarly to fighter jets, using “dead zones”—areas not visible to radar or other optical detection—to approach targets. They fly low initially, then ascend just before crashing and detonating on the target. The terrain of southern Lebanon is particularly conducive to such attacks.

But this requires skills that the terror group has honed over months of fighting against Israel. The latest attacks involved a large drone capable of carrying over 50 kg (110 lbs.) of explosives. The terrorists have likely analyzed Israel’s alert and interception systems, recognizing that shooting down their drones requires early detection to allow sufficient time for launching interceptors.

The IDF tries to detect any incoming drones on its radar, as it had done prior to the war. Despite Hizballah’s learning curve, the IDF’s technological edge offers an advantage. However, the military must recognize that any measure it takes is quickly observed and analyzed, and even the most effective defenses can be incomplete. The terrain near the Lebanon-Israel border continues to pose a challenge, necessitating technological solutions and significant financial investment.