Israel's assault on Gaza's rocket arsenals is aimed at countering what it sees as a growing strategic threat posed by Iranian-supplied missiles smuggled in through Egypt.
Though by the far the superior military power, Israel had been unable to stop the Palestinian rockets needling its southern towns over the past decade.
Since the latest flare-up of hostilities, rockets fired from Gaza have killed three Israelis, on top of a death toll of about 30 people since 2001.
The missiles, while a threat to the Israelis who live within range, are not precision-guided and sirens usually give people just enough warning to take cover before they hit. Others have been knocked down by Israel's Iron Dome interceptor system.
But among the Israelis' concerns is this: If they go to war against their arch-enemy Iran's nuclear programme, the Islamist Hamas-governed Gaza Strip could serve as a launch pad for the reprisals promised by Tehran.
By Monday, Israel said it had carried out 1,350 air strikes against Gaza arms caches and other sites. But the rocket fire persisted, hitting mostly within a 25-kilometre radius.
"The Palestinian capabilities, we can assume, have been damaged, but they remain intact as a cycle of fire has been maintained," said Uzi Rubin, an Israeli missile expert.
That may reflect the priorities of Israel's targeting.
As with its 2006 offensive against Hezbollah guerrillas in Lebanon, Israel's opening broadside in Gaza last Wednesday was against what it described as underground stores and silos of the longest-range guerrilla rockets hidden there.
The most powerful of these were Iranian-designed Fajr-5s, with 75 km. ranges and 175 kilogram warheads capable of reaching Tel Aviv or Jerusalem.
At 6 metres in length, the Fajr-5s are hard to transport and conceal. The Israelis say Iran has been manufacturing them for Hamas, which brings them in through Sudan and the Egyptian Sinai, under whose desert frontier with Gaza there is a network of smuggling tunnels.
Israeli security sources said around 20 of the Fajr-5s had been destroyed on the ground. Hamas has fired rockets at Tel Aviv four times since, though Israeli sources said some of those were less powerful variants on the Fajr, stripped of their weighty explosives for extra range and greater psychological effect.
One such example might have been the rocket Hamas fired on Friday at Jerusalem, which it called a homemade "Qassam M-75".
The Gaza arsenal is pyramid-like, with the Fajr-5s at the apex and shorter-ranged rockets stockpiled in greater numbers.
Before their current offensive, the Israelis spoke of Gaza having a total of 10,000 rockets and mortar bombs. Most of those rockets were homemade, with 15-km. ranges and dubbed Qassams by Hamas though other factions use different names.
Gaza also had a quantity – in the lower thousands, according to Israel – of imported, Soviet-style Grad or Katyusha rockets with ranges of between 20 km. and 40 km.
Palestinians have fired more than 1,100 rockets and mortars since Wednesday, an Israeli military spokeswoman said. She did not say how many more had been bombed on the ground.
Many of the Gaza rockets are in buried launch tubes that have allowed them to be fired at Israel by remote control, sparing Palestinian guerrillas exposure to counter-strikes.
How Hamas members weather the assault will prove key to further fighting. Though the faction's overall military commander, Ahmed al-Jaabari, died in an Israeli missile strike that triggered this round of violence, Hamas has local squads in Gaza's towns and camps that can, to a degree, operate independently.
More than half of the 90 Palestinians killed in the clashes have been civilians, Gaza hospitals said. Israel has said a significant number of the dead were fighters, but has published the names of just three senior figures other than Jaabari.
Should Israel escalate to an invasion, its troops and tanks would have to contend with guerrillas in Hamas bunkers and trenches that still function, Israel Radio said on Monday.
Reuters correspondents in and around Gaza also report a relative absence of Israeli combat helicopters that could provide ground forces with close support - reflecting, possibly, Israel's fear of shoulder-fired anti-aircraft missiles that have been smuggled into Gaza from Libya since last year's civil war.
We welcome your comments on the issues discussed in this article. In an ongoing effort to improve the quality of discussion at globeandmail.com, all comments will be reviewed by moderators in accordance with our guidelines. Thanks for your contributions.
Mobile users can click here to comment