Can you imagine how terrible the artillery troops who fired the shells at Beit Hanun yesterday must be feeling now? After serving in IDF Artillery, I can only say that this is every gunner's nightmare scenario: killing innocent men, women and children. In response to Kassam rocket attacks on southern Israel following the IDF withdrawal from the northern Gaza town of Beit Hanun on Monday, gunners were ordered to "fire at the source" - the spots from which the rockets were launched. And they did, firing a dozen or so shells. That, however, is a recipe for disaster so long as Palestinian gunmen launch home-made rockets at Israel from within residential areas, without really knowing where they will land, and what casualties or damage they will cause. It's like playing Russian roulette with each other. The Palestinian terrorists firing at civilian targets in Ashkelon, Sderot and other communities in the western Negev must know that the IDF can and will retaliate, and respond swiftly and strongly. THE SOPHISTICATED artillery pieces in the IDF, now computerized, are in fact capable of pinpointing targets hundreds of kilometers away. But when our gunners are ordered to fire back at the source of the Kassam launchers, they know that the results could be disastrous. Palestinian witnesses said IDF shells struck at least seven houses in Beit Hanun, killing 19 Palestinians, including 13 members of one family, as they slept. And dozens more were wounded. Defense Minister Amir Peretz immediately ordered the army to stop shelling Gaza. He gave a similar order after July's IAF strike on Kafr Kana in Lebanon, in which 28 Lebanese were killed, although the initial toll gave casualties of more than double that figure. Both Hamas and Hizbullah, in the case of Lebanon, were quick to call both attacks "massacres" and yesterday a Hamas spokesman reiterated that Israel should cease to exist. There's a key difference between the Hamas and Hizbullah fighters and Israel's. They intentionally fire rockets at civilian targets, hoping for maximum casualties and damage. We don't. The artillery troops who fired shells at Beit Hanun yesterday weren't hoping to hit civilians. They were targeting terrorists firing rockets. A CNN interviewer asked the prime minister's spokeswoman, Miri Eisin, for her response to suggestions that Israel was using "a sledgehammer to crack a nut." Eisin, like other Israeli spokespeople, was very apologetic for the "tragic mistake." And rightly so. But what does the international community expect Israel to do if it is hit daily by homemade, inaccurate rockets? Ignore them? Make our own? Fire our artillery pieces more inaccurately? Stop the Kassams, and the artillery will stop, says the IDF. Of course, the army now will carry out a thorough investigation of the tragic incident, and the necessary lessons will be learned and taught to future generations of artillery men. But the basic lesson is this: War is a dangerous game, and once you start firing rockets or guns, people will get hurt, and not always the people you plan to hurt. That's the sad fact, in a nutshell, and no one feels good about it. The writer, managing editor of The Jerusalem Post, served for 15 years in the IDF artillery.