The blame for the current fighting falls entirely on Israel’s enemies, who deploy inhuman methods in the service of barbaric goals. While I wish the armed forces of Israel every success against the terrorists in Gaza and Lebanon and hope they inflict a maximum defeat on Hamas and Hezbollah while taking a minimum of casualties, erroneous Israeli decisions in the last 13 years have led to an unnecessary war.

For 45 years, 1948-93, Israel’s strategic vision, tactical brilliance, technological innovation, and logistical cleverness won it a deterrence capability. A deep understanding of the country’s predicament, complemented by money, willpower, and dedication, enabled the Israeli state systematically to burnish its reputation for toughness.

The leadership focused on the enemy’s mind and mood, adopting policies designed to degrade his morale, with the goal of inducing a sense of defeat, a realization that the Jewish state is permanent and cannot be undone. As a result, whoever attacked the state of Israel paid for that mistake with captured terrorists, dead soldiers, stalled economies, and toppled regimes.

By 1993, this record of success imbued Israelis with a sense of overconfidence. They concluded they had won, and ignored the inconvenient fact that Palestinian Arabs and other enemies had not given up their goal of eliminating Israel. Two emotions long held in check, fatigue and hubris, came flooding out. Deciding that they had had enough of war and could end the war on their own terms, Israelis experimented with such exotica as “the peace process” and “disengagement.” They permitted their enemies to create a quasi-governmental structure (the “Palestinian Authority”) and to amass hoards of armaments (Hezbollah’s nearly 12,000 Katyusha rockets in southern Lebanon, according to the Arab daily Asharq al-Awsat). They shamelessly traded captured terrorists for hostages.

In this mishmash of appeasement and retreat, Israel’s enemies rapidly lost their fears and came to see Israel as a paper tiger. Or, in the pungent phrasing of Hezbollah’s leader, Sheik Hassan Nasrallah, in 2000: “Israel, which has both nuclear power and the strongest air force in the region, is weaker than a spider’s web.” As I wrote in 2000, “Their earlier fear of Israel has been replaced with a disdain that borders on contempt.” As Israelis ignored the effect of their actions on enemies, they perversely seemed to confirm this disdain. As a result, Palestinian Arabs and others rediscovered their earlier enthusiasm to eliminate Israel.

To undo this damage of 13 years requires that Israel return to the slow, hard, expensive, frustrating, and boring work of deterrence. That means renouncing the foolish plans of compromise, the dreamy hopes for good will, the irresponsibility of releasing terrorists, the self-indulgence of weariness, and the idiocy of unilateral withdrawal.

Decades of hard work before 1993 won Israel the wary respect of its enemies. By contrast, episodic displays of muscle have no utility. Should Israel resume the business-as-usual of appeasement and retreat, the present fighting will turn out to be a summer squall, a futile lashing-out. By now, Israel’s enemies know they need only hunker down for some days or weeks and things will go back to normal, with the Israeli left in obstructionist mode and the government soon proffering gifts, trucking with terrorists, and yet again in territorial retreat.

Deterrence cannot be reinstated in a week, through a raid, a blockade, or a round of war. It demands unwavering resolve, expressed over decades. For the current operations to achieve anything for Israel beyond emotional palliation, they must presage a profound change in orientation. They must prompt a major rethinking of Israeli foreign policy, a junking of the Oslo and disengagement paradigms in favor of a policy of deterrence leading to victory.

The pattern since 1993 has been consistent: Each disillusionment inspires an orgy of Israeli remorse and reconsideration, followed by a quiet return to appeasement and retreat. I fear that the Gaza and Lebanon operations are focused not on defeating the enemy but on winning the release of one or two soldiers — a strange war goal, one perhaps unprecedented in the history of warfare — suggesting that matters will soon enough revert to form.

In other words, the import of hostilities under way is not what has been destroyed in Lebanon or what the U.N.Security Council resolves; it is what the Israeli public learns, or fails to learn.

Mr. Pipes (www.DanielPipes.org) is director of the Middle East Forum and author of “Miniatures” (Transaction Publishers).