Yesterday, when he eulogized Dan Shomron, the 13th chief of staff who was his immediate predecessor and his friend, Defense Minister Ehud Barak said that Shomron was "one of the Israel Defense Forces more daring architects, and at the same time one of its more level-headed ones."

Israel is now in need of such a combination of daring action and good judgment, in light of the escalation in the attacks on its communities from Sderot to Ashkelon.

The dozens of rockets that were fired yesterday from the Gaza Strip - one of which killed Roni Yehiah, a 47-year-old father of four - have placed the IDF on the threshold of a major raid into the Palestinian territory. Crossing this threshold is soon liable to be seen as a necessity that cannot be condemned, but it can still be prevented.

Responsibility for the escalation lies entirely with the Palestinian side; in other words, the Hamas government. We can only imagine what would happen had the Palestinians launched rockets southward into Egyptian territory. We can assume that Egypt would protect its sovereignty and the welfare of its citizens with a tough response directed at the sources of the firing.

Israel is entitled to preserve its sovereignty, which is violated daily by steep-trajectory firing and occasionally by underground activity as well. Its citizens deserve protection from the Qassams.

At present there is no system for intercepting the Qassams, nor is there sufficient protection from them. Even when the development of security measures is completed and the protection is expanded, tens of thousands of Israelis will remain exposed to the Qassams, the Katyushas and the Grad missiles. The IDF's preventive activities against the armed squads, most of them from the air, are justified. They cannot serve as an excuse for the rocket barrages.

What is delaying the IDF's ground operation in Gaza is no longer the fear that a return to the territory from which Israel withdrew in the summer of 2005 will be an admission of failure. The government has an obligation to address present needs and future considerations. Even when our blood is boiling, the calculation has to be cold in terms of cost-effectiveness: Can the IDF expect to pay an intolerable price in casualties when it enters the territory and until it knows how to leave it, and to what extent and for how long will this remove the threat of steep-trajectory terror from its citizens?

After the severe attack at the Tel Aviv Dolphinarium in June 2001, Ariel Sharon said that "restraint is strength." Sharon stopped thinking so nine months later, after hundreds had been killed, and after the mass murder in the Park Hotel in Netanya. It's true that in the South there have been fewer casualties, but Israel has been restraining itself for a far longer time, to the point where restraint can no longer be seen as strength.

Although the situation has worsened, a massive invasion of Gaza is not unavoidable, if outside forces can be harnessed to decree restraint on Hamas. Primarily U.S. President George W. Bush and Egyptian President Hosni Mubarak, whose senior emissaries are investing a great deal of diplomatic effort which has been unsuccessful so far in cooling the flames. The U.S. secretary of state and the Egyptian intelligence minister, both of whom are scheduled to arrive in Israel in the coming days, can and must make it clear to Hamas that if Israel is pushed into crossing the fence in Gaza should the efforts fail, the world will be understanding.

The decision as to whether, how and when to embark on an operation will remain in Israel's hands. We must hope that this decision will be both daring and level-headed.