Hamas said Wednesday that it regarded the Israeli Air Force’s killing of its military chief, Ahmed Jabari, as a declaration of war by Israel. Israel is not seeking all-out conflict with Hamas, military and political sources quickly made clear on Wednesday afternoon — but it is certainly braced for the possibility.

“I oppose a ground operation,” Eli Yishai, the Shas leader and deputy prime minister said. “I hope [the conflict] won’t deteriorate into an unnecessary escalation… But it’s up to the terror groups in Gaza… If they continue…” He left the sentence unfinished.

What Israel emphatically is seeking in “Operation Pillar of Defense” is to remake the rules, and ultimately restore the IDF’s deterrent capacity, as regards the Hamas-controlled Gaza Strip. The south of Israel “cannot be held hostage” to the whims of Hamas, noted the Likud’s Education Minister Gideon Sa’ar.

The initial operation involves the use of air power, not ground forces. The opening strikes targeted Jabari and other key Hamas military figures. Other key targets are what is believed to be the limited stock of Hamas’s most potent, Fajr-5 missiles, which can reportedly reach as far north as the Tel Aviv area. Rocket-launch cells will also be relentlessly targeted, as well as other Hamas military stores and positions, the sources said.

“We had made clear in recent days that we need absolute quiet on the border,” said another deputy prime minister, Dan Meridor. “We didn’t get it.” The constant threat to the residents of southern Israel “had to be addressed,” he said.

Yishai noted that a violent Hamas response could be anticipated. “But the residents of the south are more than willing to put up with that,” he said, “if ultimately the operation achieves its goal.”

Much of the Israeli spectrum, including key figures in the opposition Labor and Kadima parties, former prime minister Ehud Olmert, and former foreign minister Tzipi Livni, quickly signaled their support for the operation in its initial dimensions. Such widespread support is unlikely to hold, however, if the military operation widens dramatically.

Gilad Erdan, the minister of environment, and Likud hawk Danny Danon quickly demanded that the targets extend to Hamas’s political leaders, including Gaza Prime Minister Ismail Haniyeh. “I hope the Hamas political leadership will have to fear for their lives,” said Erdan. “To me there is no difference between Ahmed Jabari and Ismail Haniyeh. Their blood is on their heads.” No such widening of scope was confirmed by political or military sources, however.

The resort to escalated force followed a radical escalation of attacks on the south in the past four days, which began with the targeting of an Israeli army jeep that was on a routine patrol inside the Israeli border — more than 100 yards inside the Israeli border, that is — with an anti-tank missile, in which four soldiers were injured, one of them very seriously.

Israel’s initial retaliation at what it said were Hamas terror targets was met with a major upsurge in rocket attacks — more than 160 rockets and other projectiles launched into the south.

Prime Minister Benjamin Netanyahu apparently agonized about launching an escalated response. But he and other political and military chiefs also made plain that there was a limit to Israel’s capacity for restraint.

Home Front Defense Minister Avi Dichter noted earlier this week that Hamas and other groups have fired some 11,000 rockets at Israel since 2001. The residents of the south have long since been part of the Israeli front line, he said. Another generation has been traumatized by alarms and rocket fire.

In 2008-9, Israel launched Operation Cast Lead, with unclear objectives — a three-week assault that did involve the use of ground forces. The political leadership seemed uncertain, even as that operation was under way, whether it was intended to bring tranquility to the south or to bring down Hamas altogether.

Wednesday’s ”Operation Pillar of Defense,” by contrast, seemed more clearly delineated — focused on Hamas terror chiefs, rocket crews, weaponry and other clear Hamas targets.

But the IDF’s Spokesman Yoav Mordechai noted that the political echelons “have not set any limitations.”

“We have a green light to do whatever is necessary to remove the threat” to the south, he said. “We’ll see how it develops… The IDF is at the beginning of its operation. It will continue.”