Israel claims to have destroyed the missiles of Hamas they feared most--or at least the ones they know of. But the assault on the Palestinian coastal enclave may go on for weeks.

MARCO LONGARI / AFP / Getty Images A Palestinian man calls for help as he and others try to save a man trapped under his car just after an Israeli air raid on the area of Twaam in the northern Gaza town of Beit Lahia on Nov.15, 2012.

It’s hard to get much speed on Gaza City’s cramped streets, so the sedan carrying Ahmed Jabari was easy to track from overhead as it slid past a minivan and edged into the intersection where the Israeli missile reached it at a few minutes after 4 o’clock Wednesday afternoon. The fireball singed the trees on either side of Omar al-Mukthar Street, killed the head of Hamas’ military wing and announced an Israeli military campaign that in terms of tactics began as a thumping success.

First there was a feint. In the hours before waves of warplanes and drones began firing into the Gaza Strip , Israel’s civilian and military leaders had pretended great interest in a border 200 miles to the north. The Golan Heights was where errant Syrian shells had landed earlier in the week, prompting the first exchange of fire since 1973. In Gaza, the Jewish state was assumed to be observing the latest cease-fire brokered to end the latest round of missile launches toward Israel’s southern communities, and Israeli answering with fire into Gaza. Though the tempo had quickened in recent weeks, the call and response was a rhythm both sides had grown accustomed to over the five years Hamas has ruled the coastal enclave. As the shadows lengthened on Wednesday afternoon, there was surely tension in Gaza – the buzz of Israeli drones makes tension an audible thing. But the shocked first reactions of Hamas leaders to the Jabari hit told Israeli eavesdroppers that the surprise in Gaza was profound.

What followed was certainly stunning: a lightning flurry of 20 more Israeli airstrikes, each targeting launch tunnels and storage depots for Fajr-5 missiles. An Israeli military official tells TIME that the strikes destroyed seven of the Iranian-made missiles – the entire known inventory the Israelis knew to be inside Gaza. The Fajr-5 has been Hamas’ most prized and closely guarded weapon, the only rocket capable of reaching Tel Aviv, and thus altering the agreed-upon terms of the conflict. In a matter of minutes, the Israelis may have removed – or greatly reduced – the opportunity for Gaza militants to expand the frame of the existing war, or, more significantly, a future one: The medium-range missiles could also have been launched in retaliation for any possible future Israeli attack on nuclear facilities in Iran, which provided the Fajrs in the first place.

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However, there clearly were more than seven: a Fajr landed in a suburb of Tel Aviv late Thursday afternoon, and shortly after dark the reverberations of a large explosion drove people indoors at Jaffa’s ancient port, located well inside Tel Aviv city limits. An addled-looking man on the bicycle path below Kedem Street told TIME the rocket landed in the sea directly in front of where he was casting, standing in ankle-deep water atop the shoals immediately north of a public beach near the Peres Center for Peace, at the city’s southern border. He dropped his pole and complained he was unable to find it in the dark. The last time Tel Aviv has been hit by such an attack was in 1991, by an Iraqi Scud rocket launched by the regime of Saddam Hussein.

The wail of sirens shook Tel Avivans and was was almost certain to sharpen the Israeli assault. Israeli defense minister Ehud Barak vowed “the other side will pay a heavy price for this escalation.” The Israel Defense Forces were preparing to mass ground forces that officials say they hope will not be used. But air and tank strikes — which exceeded 200 after 24 hours, according to the Israeli military — will continue to target military storage sites, revisit previous targets, and continue pursuing prominent militants in what a campaign a senior Israeli officer describes as “attrition.” “It won’t be a few days,” the officer tells TIME. “It might even be two or three weeks. This won’t end quickly.”

For Israel, the assault on Gaza has multiple aims. The most immediate is to intimidate the Islamist militants who operate out of the coastal enclave. Hamas, which has governed the 1.6 million Palestinians there since 2007, is an Arabic acronym for Islamic Resistance Movement. The message from Israel is: “Resistance is futile.” The defense doctrine of the Jewish state boils the phrase down to a single word, “deterrence,” and its restoration was the essential point of Operation Pillar of Defense, as the Israeli military dubbed the campaign in English.

It’s a delicate business, however. Israeli officials make clear they do not want to destroy Hamas, which though categorized as a terrorist organization is nonetheless the most moderate group currently operating in Gaza. It has launched missiles only rarely since the last offensive Israel launched, in December 2008, in which 1,400 Palestinians were killed, at least half of them civilians. Since then, most rockets are fired by other militant groups, such as the Iranian-backed Islamic Jihad, and an assortment of Salafist groups like the Army of Islam.

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Hamas actually worked hard to prevent the launches – most of the time. Occasionally it looked the other way, and on rare occasions even joined in the firing, mostly to demonstrate it hadn’t gone pacifist. Since surprising even itself by winning parliamentary elections in Gaza and the West Bank in 2006, notes Benedetta Berti, a researcher at the Institute for National Security Studies in Tel Aviv, “Hamas has always had the same dilemma, and they’ve always dealt with it the same way: In order to stay in power, they need to deal with Israel, they need stability, so they have to make sure things are almost quiet. But if it’s entirely quiet, they lose credibility and people defect from the Iz ad-Din al-Qassam Brigades,” the military wing of Hamas.

“Up until yesterday we had pretty clear rules of the game,” says Berti, who recently co-authored a book on Hamas and Hizballah. “Hamas through the Iz ad-Din al-Qassam Brigades basically was policing the border for Israel 90% of the time. Then every few months we had these short-lived escalations ended by a cease-fire, then we had a few months of relative calm.” In recent months, however, the escalations became more frequent, and the calm more relative. The increase in attacks reflected a change in policy within the organization. The number of rockets launched into Israel — where a million civilians were vulnerable, running to shelters when sirens sounded — increased after Hamas’ longtime political chief, Khaled Meshaal, failed to persuade a majority of the leadership to set aside violence and join forces with Mahmoud Abbas, the leader of the secular Fatah movement and head of the Palestinian Authority, which governs the West Bank, the other Palestinian territory. Abbas, also known as Abu Mazen, argues for ending the 45-year Israeli occupation through nonviolent means, including a current effort to win recognition as a state from the United Nations General Assembly on Nov. 29.

Hamas covets legitimacy as well but appears trapped in its own militancy. Israel’s new offensive is clearly intended to demonstrate the wiser course is to mature into a wholly political entity. But as Berti observes, that’s no easy task. “The question is if you can really get the organization to decide who they are with military force,” she says. “It could backfire.”

The dangers grow the longer the Israeli offensive goes on. On Thursday, three Israelis were killed when a Gaza rocket exploded on the apartment balcony where they stood. Another of some 250 missiles fired out Gaza since Wednesday wounded three Israeli soldiers. (Israeli casualties are greatly reduced by the Iron Dome missile interception system, which knocked down 100 missiles in the first day.) Inside the Strip, the Palestinian death toll stood at 15, including the three people in Jabari’s car. The total will surely rise if Israeli forces move on to targets closer to civilians. Gaza is among the most densely populated places on the globe, and on Thursday Israeli planes were dropping leaflets warning Gazans to steer clear of militants and locations associated with them.

The militants themselves were lying low. Israeli intelligence, which has many informants across Gaza, noted that Hamas’ leaders stayed away from Jabari’s funeral on Thursday, a telling level of wariness for a command that had been caught unawares repeatedly in the previous 24 hours. “They didn’t know they’d reached the stage where they forced us to strike,” an Israeli military official tells TIME. “They were also surprised by how exposed they were – both Jabari, and the Fajrs.”

With reporting by Aaron J. Klein/Jerusalem

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