According to Israel's Defense Minister, Ehud Barak, the first purpose of in launching Pillar of Defense, the country's most recent Gaza campaign, was "to strengthen our deterrence." Now that the operation has concluded, there appears to be little confidence in Israel, at least outside of the Netanyahu government troika that negotiated a cease-fire agreement with Hamas, that Pillar of Defense will deter Hamas from much of anything. And looking on is Iran. If Israel can't deter a thuggish terror outfit like Hamas, how is it going deter its larger and infinitely more dangerous sponsor, Iran? One thing is certain, Israel will never, and has never deterred its enemies by launching operations in which the stated goal is deterrence.

It is not that Israel's enemies cannot be deterred. Despite the unending enmity and hatred of the three major Muslim Arab states that directly border it (Egypt, Jordan, and Syria) Israel has, since 1948, emerged as a relatively secure and powerful regional state, increased its population ten-fold, and given its population a standard of living that rivals the most prosperous Western states, and absolutely shames those Arab states in practically every meaningful category of economic success, military power, freedom, and just, effective governance. Egypt, its most powerful enemy, concluded a formal peace agreement three decades ago. Jordan followed suit twenty years ago. Syria, which remains implacable, has nonetheless maintained a truce for nearly 40 years.

But these successes were not won by Israel's pursuit of deterrence. Rather they were the result of four bloody full-scale wars waged between 1948 and 1973. In those conflicts, Israel did not fight to deter its enemies but to defend its borders, seize territory from which the Arabs launched attacks, and destroy Arab armies.

Arab nations were not deterred from war by any deliberate Israeli policy of deterrence but by traditional wars, waged with traditional objectives. Deterrence was just a salutary side effect of actual repeated military success.

Beginning in the late 1970s, facing nontraditional, nonstate enemies, Israel began waging wars of deterrence with much less success. In 1978 and again in 1982 Israel went into Lebanon with the stated purposes of driving back PLO terrorists (and Syrian anti-aircraft batteries), deterring further attacks, and securing Israel's northern border, rather than defeating or annihilating its enemies. The result was that even when the Israelis secured military successes (as at the outset of the 1982 campaign) they were unable to translate them into tangible long-term deterrence. Because neither the IDF nor the Israeli public had been prepared for a war of annihilation against the PLO, the Israeli leadership hesitated at critical junctures, allowing the PLO to escape, and turning early military successes into perceived failures.

Israel persisted in this inconclusive policy against Hezbollah, which replaced the PLO on Israel's northern border. In 1993 (Operation Accountability) and 1995 (Operation Grapes of Wrath) Israel launched standoff air and artillery attacks against Hezbollah without success, but engendering international disapproval when civilian human shields were killed. In 2000, Israel gave up against Hezbollah and pulled out of Lebanon.

This led to the 2006 War against Hezbollah, which though widely perceived as an Israeli defeat, nonetheless has produced a quiet northern border for the past six years. The Israelis made many mistakes during the 2006 campaign, first among them, approaching it from the outset as an operation to retaliate for a Hezbollah attack and compel the Lebanese government to rein in and control the organization. But a few days into the campaign, when it appeared that Hezbollah was not being deterred and that the Lebanese government was unable or unwilling to act, Israel appeared to change its rhetorical tune, with Israeli officers and ministers speaking of destroying Hezbollah -- a traditional military objective.

The true objectives of Israel's 2006 operation are unclear and subject to debate even to this day. It's not certain that Israel's leaders ever had a firm idea of what they wanted to do. However, once Israel reoriented the mission, or mission rhetoric, to destroying Hezbollah, or at least its organization in Southern Lebanon (in fact the new operation was dubbed "Change of Direction"), it seems to have had long-term deterrent effect (although this was not necessarily apparent at the time or shortly thereafter). Like Hamas, Hezbollah fired rockets into Israel until the end of the war, but they have not fired any rockets since.

Israel failed to destroy Hezbollah or even most of its infrastructure in South Lebanon, which allowed Hezbollah to declare "victory" in the war. Despite this, Hezbollah was apparently been deterred. Had Israel escalated more, attacked Syrian supply routes, and pressed the attack further, the results would have likely been better. Still, the Lebanese border has remained quiet for six years now, a nearly unprecedented period in Israel's entire history. Hezbollah's loquacious leader Hassan Nasrallah is judged the ultimate intensity of the Israeli response and has since gone to ground, rarely emerging. The war was a defeat for Nasrallah too.

Still, the IDF's overall performance in the 2006 War was disturbing enough that Israel established the Winograd Commission to investigate the reasons for the campaign's shortcomings, and recommend reforms. One of the commission's findings was that "standoff fires," like the air and artillery strikes that solely comprised Pillar of Defense, were an ineffective tactic for stopping or deterring rocket fire.

When Israel launched Operation Cast Lead four years ago, it combined standoff fires and a ground attack with great success. Indeed, Israel might have easily destroyed Hamas had it pressed its attack for a few more days. Its failure to do so convinced Hamas that Israel lacked the will to destroy it, and Hamas quickly returned to its policy of intermittent rocket fire which finally provoked Pillar of Defense. There is no reason to assume that such a standoff operation, which was castigated by the Winograd Commission, will work to deter Hamas today. Indeed, the reason Hamas launched a dozen missiles right after the "cease-fire" went into effect, was to make just that point.

The only way to deter a radical Islamist organization like Hamas or Hezbollah is to destroy it -- or at least try. Hamas, Hezbollah, or Iran will not be deterred by military operations whose stated purpose is to deter. They are not deterred by conventional considerations like casualties, damage, or civilian loss. To win, all they must do is launch one more attack.

A nuclear armed Iran (which seems likely) must be deterred from launching its own attack. Iran will certainly not be deterred if it believes that Israel will hesitate to launch an annihilating attack in return. For Israel, the stakes of letting Hamas fight on another day are greater than whether that organization will be able to launch missiles in the future. It is the message Israeli restraint sends to its most potent enemies.

Since 2006 Hezbollah has rearmed, and in the interim, the deterrent effect of the 2006 campaign will have eroded. Hezbollah and its patron Iran have certainly closely watched Israel's operation in Gaza, and to the extent they perceive a lack of resolve, will test Israel again. Which is all the more reason why Israel's early termination of Pillar of Defense may well come back to haunt it.

Jonathan Keiler's novel of the Holocaust, Upfall, is available for sale at Amazon.com and other online outlets.