Pop quiz: How many Israelis were killed by Palestinian terror in the intifada's third year - the one that began in September 2002, six months after Operation Defensive Shield?

Answer: 240.

You read that right. In the year following the operation that, according to Israeli mythology, vanquished terror, 240 people were killed in terror attacks - one of the highest annual tolls for terrorism-related deaths in the country's history.

Does that mean Defensive Shield was actually a failure? Not at all. The real Defensive Shield was every bit the dramatic turning point Israelis think it was. Unfortunately, the real operation has been obscured by the legend.

The 240 killed in the intifada's third year nevertheless represented an enormous improvement - a 47 percent drop from the previous year's 449 fatalities. Moreover, fatalities continued dropping by about 50 percent a year in subsequent years, hitting a low of eight just four years later. That is why Defensive Shield is justly remembered as a huge success: It was the start of the process that produced this achievement.

THE OPERATIVE word, however, is "start." Defensive Shield was not, as legend has it, a magic bullet - a one-time operation that, by its end a few weeks later, had completely destroyed the terrorists' capabilities and/or motivation, thereby allowing our troops to withdraw and us to live happily ever after.

The government may have hoped that would be the case; it withdrew the IDF once the operation ended. But that withdrawal was followed by June 2002, the second-worst month of the entire intifada, with 58 killed. Consequently, the army was sent back in. And this time, it never really left. The IDF controls the entire West Bank to this day, operating freely wherever and whenever it chooses.

And that is the real key to the subsequent steady decline in Palestinian terror. Defensive Shield was the turning point because that was when the IDF first reentered West Bank cities after an eight-year absence. But it was the army's continuing presence that produced the achievement for which Defensive Shield alone is too often erroneously credited.

THERE ARE three reasons for this. First, no single operation can possibly eliminate all the terrorists' capabilities. No matter how good our intelligence is, some key operatives will escape, some weapons caches will remain undetected, and so forth.

Second, as the intelligence agencies freely admit, their capabilities are curtailed in places we do not control, due to factors ranging from the difficulty in arranging face-to-face meetings (which the agencies say are critical to getting the most from informants) to the fact that there are fewer carrots and sticks to wield under such circumstances. Hence ongoing control over the West Bank is what enabled these agencies to progress from being repeatedly surprised by suicide bombings to receiving precise advance knowledge of most of them. This is also why, as the agencies themselves acknowledge, they have much better intelligence about the West Bank than about Gaza.

Finally, and most importantly, once the army withdraws, there is nothing to stop the terrorists from rearming and regrouping. That should be obvious to anyone who observed Hizbullah after the IDF left Lebanon in 2000 or Hamas after the IDF left Gaza in 2005: Both organizations exploited the IDF's absence to import massive quantities of arms, recruit and train troops and dig fortifications. Nothing similar has happened in the West Bank because the IDF has been there continuously, enabling it to intercept arms deliveries and arrest new recruits.

It is that slow, step-by-step work over the course of years - gathering intelligence, carrying out raids and arrests - that gradually eroded the terrorists' capabilities in the West Bank to the point where suicide bombings have become a distant memory. Indeed, just how essential that ongoing presence was became clear every time international pressure forced us to return a city to the Palestinian Authority: Each time, terrorist activity in that city quickly resumed, resulting in a deadly suicide bombing and the IDF's return.

DOES THAT mean the IDF must remain eternally in any place from which Israel wishes to prevent attacks? Clearly not. There are no IDF troops in Jordan or Egypt, for instance, yet neither is there any cross-border terrorism.

Those countries, however, have governments that are willing and able to control their terrorists. Without such a government, there is no substitute for IDF control - because terrorists stop shooting only when forced to do so.

And that is precisely the problem in Gaza, where the terrorists are the government. The idea that Hamas will voluntarily halt terror is delusional. Nor is there any possibility of replacing it with a government that would. Even if the current IDF operation were aimed at toppling Hamas (which it is not), any Palestinian government that replaced it would lack the capability to suppress terror even if it had the will. The PA's forces in Gaza are nonexistent, and its cadre of trained troops in the West Bank is insufficient for the job even in the unlikely event that they all agreed to relocate to the Strip.

For the foreseeable future, therefore, there are only two alternatives: Either we reoccupy Gaza or the rocket fire will eventually resume, even if the current operation produces a temporary lull. It would be nice if there were a third alternative, a one-time operation that would solve the problem once and for all. But in the real world, there are no magic bullets. And while the myth of Defensive Shield has unfortunately obscured the reality, the reality proves its worth day after day: Even as thousands of rockets and mortars have been fired from unoccupied Gaza over the last three years, not one has been fired from the occupied West Bank.

Reoccupying Gaza is clearly not cost-free, and reasonable people can disagree about whether the costs of the rocket fire justify the costs of reoccupation. But the debate must be based on facts, not myths. And that starts with understanding what Defensive Shield really was: not a one-time operation, but a full-scale reoccupation that is now six years old and counting.