Updated at 3:12 p.m. ET on October 7, 2023

What a difference a week makes.

Just eight days ago, National Security Adviser Jake Sullivan, speaking at The Atlantic Festival, rattled off a long list of positive developments in the Middle East, developments that were allowing the Biden administration to focus on other regions and other problems. A truce was holding in Yemen. Iranian attacks against U.S. forces had stopped. America’s presence in Iraq was “stable.” The good news crescendoed with this statement: “The Middle East region is quieter today than it has been in two decades.”

One week later, a shocking, multifront attack launched by the Iranian-supported Hamas against Israel has turned the Middle East into a maelstrom. The assault, almost 50 years to the day after the surprise Arab attack on Israel that marked the opening of the Yom Kippur War, could represent a paradigm-shifting moment as big as 9/11. So far, more than 100 Israelis are confirmed dead and many hundreds more gravely injured in a coordinated attack by Hamas terrorists who infiltrated by land, sea, and air. A thousand tragedies will unfold—at the moment, an unknown number of Israeli civilians and soldiers might be held hostage in Gaza. As of this writing, nearly 200 are reported dead in Israeli reprisal raids. The Israeli army has activated at least 100,000 reservists, and a full-scale ground invasion of Gaza is plausible, if not probable.

Behind this moment are failures of intelligence, but also of imagination. The Israeli government, led by Prime Minister Benjamin Netanyahu, who has styled himself as “Mr. Security” for decades, will have much to answer for in the coming weeks and months. But Sullivan’s comments, made onstage in Washington to The Atlantic’s editor in chief, Jeffrey Goldberg, also suggest how little sense there was among Biden officials that something like this could happen. “Challenges remain,” Sullivan said in his comments last week. “Iran’s nuclear-weapons program, the tensions between Israelis and Palestinians. But the amount of time I have to spend on crisis and conflict in the Middle East today, compared to any of my predecessors going back to 9/11, is significantly reduced.” (His remarks begin at 58:52 in the video below.)

In the coming days, there is no doubt that Sullivan’s Pollyannaish view will be subjected to great scrutiny. Hamas, and its Iranian and Hezbollah allies, have not made a secret of their ultimate aims. Beyond wishful thinking, the cause of the hopefulness articulated by Sullivan might be this: the developing deal to establish formal relations between Israel and Saudi Arabia—a developing deal that is most likely developing no more.

The Biden administration and Netanyahu have been deeply invested in such an agreement, and the desire for it might have created a blindness among Israelis and Americans alike about what was happening just over the border in Gaza. “We wanted to try and pretend that this conflict was isolated and contained and didn’t need our attention,” Yaakov Katz, the former editor-in-chief of The Jerusalem Post, told me today hours after the invasion.

“There is clearly in his comments a perception that Iranian options for disrupting were limited,” Dennis Ross, a Middle East peace negotiator in several administrations, told me, referring to Sullivan’s earlier assertions. “You don’t make that statement unless you think the Iranian options for disrupting are limited. And obviously at this point that proves not to be correct.”

On Netanyahu’s side, an agreement with the Saudis would help distract from the ongoing domestic unrest in Israel over the judicial overhaul his right-wing coalition has sought and that has led to nearly a year of protests. For Biden, a peace agreement would help bolster his foreign policy record going into the 2024 elections—with the possible effect of erasing memories of the chaotic withdrawal from Afghanistan.

Out of these twinned interests emerged the goal of de-escalation and quiet—a noble desire, to be sure. The United States, for its part, is eager to do more than just respond to crises in the region and seems to have been genuinely caught by surprise (“There is never any justification for terrorism,” read a statement from the NSC). But it apparently didn’t take into account Iran’s capabilities for sowing such crises. Behind the Hamas attack can be seen the desperation in Tehran to avoid the chance of a handshake between Netanyahu and Saudi Arabia’s Mohammed bin Salman. (Iran, a longtime backer of Hamas, celebrated today’s attacks.)

“The attack is so extreme and unusual that it is almost impossible to imagine Israel feeling comfortable with a return to the status quo ante in Gaza,” Hussein Ibish, the senior resident scholar at the Arab Gulf States Institute, told me. A change to Israel’s control over Gaza, which Ibish sees as inevitable, will affect the negotiations with Saudi Arabia. The Saudis need a concession from the Israelis in the Palestinian conflict to move forward, which seems hard to fathom now. “The conditions and the terms and the contexts have been thrown into radical uncertainty,” Ibish said.

Ross said he doesn’t think that it’s clear the Hamas invasion will necessarily spell the end of what had been a period of less tension. “A lot depends on how this comes out. If it comes out looking like Hamas succeeded and Iran succeeded, well, then we’re looking at a region that’s going to look quite hopeless for a long time to come. But if this comes out in a way where they expended their best efforts and they ended up being set back—losing—well, then the prospects for the region can look much more hopeful.”

At the moment, it seems Iran is getting its wish, and at the expense of Gaza’s population. Israel is at war, prepared to launch a major campaign against Hamas in retaliation. Further death and destruction will surely follow. And the truism holds: The only constant in the Middle East is precipitous and dramatic change. The “quiet” that Sullivan was observing—if it ever existed as more than just a wish—is already a distant memory.

War is a perpetual concern in Israel, but it has been decades since Israelis have had to wonder whether today might be the day that their borders will be overrun and their enemies will go building to building deciding whom to slaughter. Early this morning, a few Israeli military outposts and settlements saw an apparent preview of that nightmare—an operation by Hamas that could be a daring single-day raid or the start of a regional war of a scale not seen since 1973. Hamas rocketed Israel thousands of times, then began a land-air-sea operation against targets in southern Israel. Commandos in gliders, trucks, and dune buggies raided Israeli military posts around Gaza. Images on social media show Israeli soldiers in states of dress and undress, apparently dead in the dirt, and Hamas fighters celebrating the destruction of armored vehicles and the looting of lighter ones. The images from Israel show carnage and cruelty comparable to Mesopotamia during the campaigns of the Islamic State.

Much worse than the images of dead soldiers are those of Israeli civilians seemingly having been killed in incursions into towns and settlements nearby. Some images show old women at a bus stop, their possessions still next to them, and their blood and viscera leaking from their corpses. Others—all still unconfirmed—are even worse, with indications that gunmen went door-to-door and killed indiscriminately while residents huddled in fear. More and more videos are emerging of civilians beaten and sometimes soaked in blood, either their own or others’. They appear to have been transported to Gaza as hostages. The dead are not spared this fate. Two videos I have seen suggest that Hamas has taken the corpses of Israeli soldiers to Gaza and encouraged crowds to desecrate them. A woman’s body is stripped partly naked and spat upon.

Shooting thousands of rockets at a time takes planning and covert logistical support. Coordinated commando raids take forethought as well. Failure to foresee these actions is enough to get Israeli generals and spies fired and relieved of command. A single hostage hidden away in some tunnel in Gaza can paralyze Israel for years. Now there are reportedly dozens, in addition to the kidnapped human remains and, of course, the dead, at least 100 Israelis as of this writing. Governments fall over failures of this scale. The Israeli right, led by Prime Minister Benjamin Netanyahu, has long argued that it was responsible for the relative peace that has prevailed for the past decade or so. That peace is now over. Netanyahu’s legacy is in shambles. And the only thing that might keep his government from taking full blame for the failure is the perception that the Israeli left may have flubbed things even worse.

The recriminations have just begun. But they might still be too early. So far the geopolitics of this war are only starting to be understood. Hamas has backers—Iran and Syria foremost among them—and unlike the flat-footed Israelis, they are likely to have had plenty of time to think through how the war will unfold. Hamas would not jeopardize its sponsorship by launching a war without consultation—in particular, a war whose tactics (hostage-taking, parading corpses) were calculated to enrage Israel and its friends.

The most predictable consequence of the war will be a pause in the process of diplomatic recognition between Saudi Arabia and Israel. The countries have long had a working security partnership, and it is an open secret that Crown Prince Mohammed bin Salman would, for the right price, expand that partnership to include full normalization. That is impossible while civilians on either side are dying in large numbers, and their mangled bodies being exhibited on social media. Iran will be pleased to slow down this process and maybe stop it altogether.

It is less clear why Hamas would be willing to pay such a steep price for its day of victory. Israel will sting from this attack, but in time it will respond in kind, and the Gazan dead (armed and civilian) will probably outnumber the Israeli before long. That leaves many wondering whether this surprise attack—an attack so shocking that it will harden Israel’s security posture for many years—has other phases still to come that would justify the result. The most obvious next step would be the opening of a northern front, across the Lebanon border, by Iran’s proxy Hezbollah. Israel has announced the activation of reserves and alerts in the north. But the disarray in the south is so wild that one could reasonably doubt Israel’s ability to keep things together on two fronts.

“The Middle East region is quieter today than it has been in two decades,” President Joe Biden’s national security adviser, Jake Sullivan, said last week at The Atlantic Festival. “The amount of time that I have to spend on crisis and conflict in the Middle East … is significantly reduced.” If war breaks out generally around Israel, and questions arise about Israel’s very survival, the United States will have to start counting its ammunition. How much is left for Israel, after Ukraine has taken its share? And what about Taiwan, now third in line? These are hard questions, and Iran, Russia, and China would be thrilled, collectively and separately, to force them on the United States.

Al Jazeera's team was reporting live when the Palestine Tower right behind them was struck by Israeli forces.

Cafes shut, streets empty, football games cancelled: The Hamas attacks have brought the Israeli city to a standstill.

The attacks by Hamas against Israel beginning early this morning, some that are ongoing, will be met by Israel with force. How this all unfolds, and its impact on domestic and geopolitics, is not clear, but a simple answer may suffice for now: not well. Prime Minister Benjamin Netanyahu has already warned his citizens that they are at war, civil reservists have been called up, there are videos of hand battles on the streets. The country is on lockdown, with the potential for future strikes in the south by Hamas and new ones by Hezbollah in the north. A country torn apart by domestic divisions seems to be united against a common enemy. As of this writing, the death toll is confirmed at a minimum of 70 Israelis, with hundreds of more wounded.

One aspect of this needs little analysis, but a lot of explanation: How did Israel’s extensive counterterrorism efforts fail to pick up an attack waged on land, sea, and air? How did its defenses fail so extensively? This wasn’t just an intelligence failure. It was an everything failure. Israeli and American commentators are already describing this as Israel’s 9/11, but that comparison is a crutch. 9/11 was about, in the words of the commission that reviewed it, a “failure of imagination” to understand what could happen in America, a nation that had not encountered foreign terror threats of any significant magnitude. Israel has existed, still exists, with that very imaginable prospect as part of its national being.

To focus on Israel’s preparedness in no way excuses the Hamas attacks and is not meant to blame the victim. Some on social media are carelessly suggesting that the failures can only be explained by some evil “wag the dog” effort by Netanyahu to unify the country by going to war. Israel has been attacked, and civilians are dead. As in any nation that encounters such a horror, it is essential for the government to determine—without the interference of politics or religion—why. Otherwise, enemies will take advantage of this devastating day for Israel’s counterterrorism strategy.

Israel’s counterterrorism efforts are extensive, and well supported by the United States. (As a member of the faculty at Harvard’s Kennedy School, I have taught many Israelis in homeland security and counterterrorism planning.) The Israelis infiltrate terrorist groups and pay off members for intelligence. They destroy infrastructure in Gaza as a deterrence. Family members of suspected terrorists are not off limits. Israel has long utilized assassination against its enemies in Iran and elsewhere. Signal intelligence, shared with and from allies and even Arab countries, is plentiful. Bombing raids and military excursions against Hamas are part of Israel’s counterterrorism mission.

None of this apparently picked up, or at least picked up with enough time, the signs of an attack. Just a few days ago, the Gaza border seemed to have been stabilized after some unrest, and nearly 20,000 workers were able to travel across it again. Today, thousands of rockets, which must have been obtained and hidden, were launched by Hamas. It did not end there. Hamas used drones to strike at Israeli targets. It sent its fighters on foot, by boat, and by air on motorized paragliders. Images have emerged of Hamas attackers on the streets of Israeli towns terrorizing citizens, and worse. This is as much a physical attack as a performative one: Watch us, Hamas seems to be saying. Hamas surely planned for the attack to take place on the Jewish holy day of Simchat Torah and on the 50th anniversary of the Yom Kippur War.

But that is only one piece of what Israel is going to have to reckon with from an operational perspective in the days ahead. It is one thing to not imagine such an attack could occur. It is another to seemingly not have the defense in place to be ready. Israel takes its preparation for such attacks seriously; most citizens are under mandatory conscription. It tests its response and evacuation systems regularly. It recently built an extensive technology wall—including radar, cameras, and sensors—on 65 kilometers of the Gaza barrier. Its emergency management capabilities are mature. Still, at this writing, Hamas seems to have control over several populated areas in southern Israel. Hamas’ drones seem to have penetrated parts of Israel without reports of counterdrone efforts. Iron Dome, Israel’s famous counter weapons system, was no match for a multifaceted terror campaign, akin to the 2008 Mumbai attacks in India.

Most systems under persistent attack will eventually fail. Over the course of this century, Israel has been able to stop numerous terror plots, some supported by Iran and some by other countries. It could not do so today, to spectacular effect. Not now, but soon, Israel will have to contend with how, in the modern era, it encountered a massive security failure not seen since the Yom Kippur War. Finding the answer is Israel's obligation to itself.

Speaking to Al Jazeera, Hamas deputy chief Saleh al-Arouri says group expects fighting with Israel to continue.

Israeli officials tell BBC an investigation into Gaza's surprise attack will go on for years.

The white truck is thought to be carrying Palestinian militants through the Israeli town.

Palestinians are seen jumping on the military vehicle, as smoke pours from it.

The armed wing of Hamas fired hundreds of rockets from the Gaza Strip on Saturday morning, killing at least one Israeli and ending a truce that had been generally respected since the end of a five-day war between Israel and the territory in May.