CRITICS of Israel’s campaign to defend millions of its citizens from deadly Hamas rocket fire claim that it lacks a clear objective. Israel has bombed Gaza in the past, they argue, and received only rockets in return. Is there any logic, much less an end, to the cycle of violence? Can it lead to negotiations and peace?

Such questions can be answered only by going back to the origin of the campaign that we Israelis now call Operation Pillar of Defense. It did not begin last week, after Hamas fired more than 700 rockets at southern Israel this year; nor did it start four years ago, as Israel acted to stop thousands of terrorist rockets striking its south. It did not even begin in 2005, when Israel uprooted 21 of its Gaza settlements, together with their 9,000 Israeli residents, to advance peace, and received only Hamas terrorism in return. Rather, the operation began on May 14, 1948, the day Arab forces moved to destroy the newly declared state of Israel.

There were no settlements back then, and the West Bank and East Jerusalem were in Jordanian hands. Yet the very notion of a sovereign Jewish state in the Middle East was abhorrent to the Arabs, many of whom were inflamed by religious extremism. They rebuffed repeated Israeli offers of peace, and instead launched a war of national annihilation. Israel had no choice but to defend itself, losing 1 percent of its population — the equivalent of 3.1 million Americans today — before achieving an armistice.

But few Israelis mistook that truce for peace. On the contrary, most assumed that the Arabs would eventually forget their defeat and seek a “second round.” Indeed, eight years later, in 1956, Israeli and Arab forces again clashed, and then fought again in 1967, 1973 and 1982. The periods in between were punctuated by Arab attacks and Israeli retaliations. Subsequently, in Lebanon, the West Bank and Gaza, Israel mounted major counterstrikes against terrorists dedicated to its destruction.

Throughout, Israelis never abandoned the vision of peace. Still, we came to understand that the cause of the conflict was not borders or even refugees but the same hatred of Jewish statehood that drove the Arabs to invade us in 1948. We understood that our enemies required periodic reminders of the prohibitive price they would pay for murdering our families. We also understood that defending ourselves incurred economic, diplomatic and human costs, yet there was no practical or moral alternative. The tactic is deterrence. Our strategy is survival.

Negotiations leading to peace can be realistic with an adversary who shares that goal. But Hamas, whose covenant calls for the slaughter of Jews worldwide, is striving not to join peace talks, but to prevent them. It rejects Israel’s existence, refuses to eschew terror, and disavows all previous Israeli-Palestinian agreements — the terms established by the United States and the other members of the so-called quartet of Middle East peacemakers for participation in the peace process. Bound by its genocidal theology and crude anti-Semitism, Hamas cannot be induced to make peace. But it can be deterred from war.

This was the case with Hezbollah in Lebanon. Like Hamas, Hezbollah is an Islamist organization committed to Israel’s demise. It, too, ambushed Israeli soldiers on our side of the border and rained rockets on Israeli towns. Then, in 2006, Israel struck back, destroying much of Hezbollah’s military infrastructure, neutralizing its long-range missiles, and killing hundreds of terrorists. Hezbollah internalized the message, and since then its missiles have remained inert. The people of northern Israel, meanwhile, have enjoyed six of their quietest years ever.

This does not mean that the tactics of deterrence and the strategy of survival cannot result in peace. Egypt and Jordan tried more than once to defeat Israel militarily, only to recognize the permanence of the Jewish state and to sign peace accords with it. Similarly, the Palestine Liberation Organization, guided by nationalism rather than militant theology, realized it could gain more by talking with Israel than by battling us. The result was the 1993 Oslo Accords, the foundation for what we still hope will be a two-state solution. By establishing deterrence, Israel led these rational actors toward peace.

Unfortunately, Hamas is not rational. It targets Israeli civilians while hiding behind its own. During a campaign of murder and kidnapping in 2006 and 2007, it gunned down members of its rival, Al Fatah, in the streets. Its covenant says Christians and Jews “must desist from struggling against Islam over sovereignty in this region”; under its rule, militants firebombed a Christian bookshop. It celebrated 9/11 and mourned the death of Osama bin Laden. We hope some day to persuade its leaders to make peace with us, but until then we must convince them of the exorbitant price of aggression.

Back in 1948, we envisaged a future of security, prosperity and mutual respect with our neighbors. We still cling to that dream. But we must also remain vigilant and, occasionally, neutralize the rockets and combat the terrorists that target us. President Obama said Sunday in Bangkok that “we’re fully supportive of Israel’s right to defend itself from missiles landing on people’s homes and workplaces and potentially killing civilians, and we will continue to support Israel’s right to defend itself.” Earlier in the trip, his deputy national security adviser, Benjamin Rhodes, said that Israelis would “make their own decisions about the tactics they use.” Those tactics, together with our survival strategy, have helped us to create one of the world’s most vibrant and innovative societies, while enabling us to pursue peace.