Hamas warned Israel on Wednesday that it had opened “the gates of hell” in targeting Gaza’s notorious terror chieftain Ahmed Jabari.

In truth, however, a reluctant Israeli government — Israel has no desire to be drawn into prolonged military conflict with the Hamas-ruled Gaza Strip — plainly felt it had little choice but to launch Operation Pillar of Defense, an escalated air assault on Hamas targets.

The incident that prompted this latest drastic flare-up on Israel’s southern border saw an anti-tank missile fired at an Israeli army jeep that was traveling not on the Gaza side of the border, as was erroneously claimed in some initial reports — nor even on the very border line itself — but rather making a routine journey some 150 yards inside sovereign Israeli territory. As the father of one of the four soldiers who were in that jeep noted, it was “miraculous” that all four were not killed in the unprovoked attack. All four were injured, however, one of them very seriously.

More profoundly, the norm by which Israeli troops could reasonably expect to not be attacked by high-precision enemy fire when moving about fairly far inside that part of sovereign Israel was violently shattered. There is a precedent for such developments, and it is a precedent Israel is anxious not to see repeated.

After Israel abandoned its security zone in southern Lebanon in 2000, withdrawing to the international border, the army gradually pulled back from the border over the years, allowing Hezbollah to deploy right up against the northern fence. From there, Hezbollah was able to launch cross-border attacks at will, as it did at the start of what became the 2006 Second Lebanon War. The IDF is evidently insistent that no repeat process unfold regarding Gaza.

Hamas might argue that the current escalation did not begin with the attack on the IDF jeep at all, but rather a few days earlier, when Israel discovered and blew up a highly sophisticated tunnel that had been dug under the border, and IDF troops briefly entered Gaza in the course of defusing the threat. The Hamas goal, after all, is to gradually reverse the balance of deterrence — to create a situation in which Israel is wary of patrolling too close to the border, wary of entering even briefly and not far into Gaza, and ultimately altogether wary of confronting Hamas.

That way, the Islamist terror group gets to develop its forces, Hezbollah-style, until it comes to constitute a major strategic threat.

That way, in the interim, it gets to dig tunnels at will. It wins a free hand to use those tunnels to kidnap soldiers — as it captured Gilad Shalit and killed two of his colleagues via just such a tunnel in 2006, ultimately securing the release of more than 1,000 Palestinian security prisoners in a radically lopsided prisoner exchange. It gains the upper hand at the border.

And ultimately, that way, Hamas gradually creates a situation in which, even as it improves its rocket and missile resources and other terrorist capacities, and even as it fires at will into southern Israel, the IDF is deterred from intervening.

This is a process Israel’s southern citizenry cannot tolerate. It is a process that Israel’s military chiefs evidently felt they could not tolerate. And the word from the IDF on Wednesday was that the political echelon had not imposed any limitations on the air-led assault on Hamas personnel, weaponry and infrastructure.

But there is a precedent, too, for the kind of operation the IDF is now pursuing: Operation Cast Lead, four years ago. Then, too, the IDF embarked upon an assault on Hamas, publicly presented as being intended to restore tranquility to the south. But though the military planning was exemplary, the scope of the operation did not appear to have been firmly determined by those who had planned it. Was the IDF supposed to hurt Hamas or to oust Hamas? The IDF itself did not know, because its political stewards — notably Defense Minister Ehud Barak — vacillated. And as the operation unfolded over three weeks that winter, the lack of clarity became apparent, and damaging.

Two years earlier, the vagueness of the political chiefs’ military objectives had yet more serious repercussions in the 34-day Second Lebanon War. With an untried prime minister in Ehud Olmert, and an unsuitable defense minister in Amir Peretz, a limited operation metamorphosed into a full-scale war, with predictably dismal consequences.

Barak on Wednesday said the aims of Pillar of Defense were to bolster Israel’s deterrent capability, to attack the rocket launch infrastructure, to badly damage Gaza’s terror cells and to reduce the attacks on Israel’s citizenry. Laudable goals, of course, which most Israelis would wholeheartedly endorse. But rather vague, too.

Does Israel intend to invade the Strip, and demolish Hamas? Almost certainly not. That could involve retaking responsibility for well over a million hostile Palestinians — an immense, protracted, draining reversal, sought only by the Israeli far-right, and regarded with horror by most Israelis. So how far short of that is this operation intended to halt?

The resort to force is widely regarded in Israel as both overdue and unavoidable. The wisdom of the operation’s stewards, however, will lie in knowing how and when to de-escalate — in recognizing when all that can reasonably be achieved has been achieved.