The Israel Defense Forces has presented the conclusions from its probe into what went wrong in the lead-up to Oct. 7, 2023 that enabled Hamas’s deadly invasion. Many of the lessons have been discussed throughout the war on a general level, but two key takeaways stand out: one, that it is now impossible for Israel and the region to go back to the pre-10/7 status quo, and two, that it cannot expect the Israeli public to believe what it cannot see. The attitude toward the government will henceforth be: trust, but verify.

The IDF analysis covers nearly a decade up to the current war, beginning from Israel’s 2014 counteroffensive in Gaza. The Times of Israel’s Emanuel Fabian has a clear bullet-pointed list of the mistakes and conclusions and lessons learned, but in a way they’re all part of a subset of one overarching mistake: The security and political establishments underestimated Hamas. Everything else flows from that.

Israel did not believe that Hamas wanted, or was capable of carrying out, a full-fledged total war. But it did, and it planned for it, and here we are.

“Israel believed that leveraging improved civil conditions in Gaza would make Hamas less likely to launch a war,” Fabian writes. “Israel worked to have defenses ready for rounds of conflicts lasting several days and the possibility of it deteriorating into a war, during which the IDF could attack and degrade Hamas’s force build-up. At the same time, Israel worked to reach some level of agreements with Hamas to improve the civil conditions in the Strip. In hindsight, Hamas’s efforts to reach understandings with Israel were part of a deception campaign to trick Israel into thinking it was uninterested in war.”

Any and every drop of legitimacy Israel gave Hamas in the name of improving Palestinians’ lives was paid back in Israeli blood. The result of Israel thinking it could coexist with Hamas was devastation for everybody. Hamas’s ultimate defeat is imperative for Israelis and Palestinians alike; neither can afford to leave Hamas intact. And that is an important lesson for the self-proclaimed pro-Palestinian advocates of the world as well.

As for the second major takeaway: The border fence separating Israel from Gaza was intended to represent merely a part of a larger security network that was mostly out of sight. But the reliance on detection technology, which Hamas was able to disarm, meant that there really only was a fence separating the two. Good fences make good neighbors; Israel did not have either.

But the principle goes for the IDF as well: The Israeli establishment misjudged the extent of Hamas’s tunnel construction underneath Gaza. They, too, couldn’t see the entire playing field because part of it was underground, but they were pretty sure they would know if the reality was significantly different from their expectations. It was, and they didn’t know.

The report has important implications for Lebanon, too. Israel expected Hezbollah to represent the greatest threat on its border. But Hamas’s increased threat didn’t make Hezbollah any less of a threat than it already was, regardless of which one posed the more immediate danger to Israeli civilians. Simply put, Hezbollah (and forces similar) cannot be allowed to put Israel in that situation ever again. If you’re wondering why Israel is taking such a serious approach to any perceived threats materializing in the chaos of Syria’s transition, this should answer that question as well.

Israel—and the region more generally—paid dearly for the belief that as long as these terror groups kept their boots off Israeli soil they were a manageable threat basically at all times. The prevention of another devastating regional war depends on Israel not repeating that mistake, no matter how much the rest of the world wants it to.