The Kassam rockets launched against Israel over the past five years continue to harass the country despite its unilateral withdrawal from Gaza. The Kassam is a simple steel rocket filled with explosives. The rocket lacks a guidance system, but its users have succeeded in expanding its range from three kilometers to 10, rendering an increasing number of Israeli targets vulnerable to Kassam fire. While some of the rockets have landed in Palestinian areas due to malfunctions, most have fallen within Israel causing, however, only limited damage and a few casualties. Yet, the Kassam, a low-tech weapon, has turned into a serious challenge to Israel's national security. The Palestinians have begun to use the evacuated area in northern Gaza to target Kassams on the southern outskirts of Ashkelon - the location of valuable infrastructure targets such as power and desalination plants, as well as the installations of the Ashkelon-Eilat oil pipeline. Moreover, an additional extension of the Kassam's range could make most Israelis hostage to the whims of Palestinian terrorists, particularly if Kassams are launched from the West Bank. Palestinian cities such as Tulkarm, Kalkilya and Ramallah have a much richer menu of potential Israeli targets (in both population and infrastructure) than Gaza. Until Wednesday, when the IDF declared a buffer zone in northern Gaza, its response to Kassam attacks was patently inadequate and demonstrated a clear lack of deterrence. For long months the defense establishment simply failed to deal with this issue. No defensive system to intercept Kassams is yet available. Air strikes against the workshops that manufacture the rockets in the Gaza Strip have not halted production. Efforts to block the import of the chemicals needed to produce explosives have been similarly unsuccessful. And Israel's threats that after withdrawal from Gaza the Israeli response to Kassam attacks would be extremely harsh have hitherto resulted in artillery barrages into "launching areas" - empty fields. This is hardly conducive to enhancing deterrence. The Palestinians count on Israel's reluctance to attack targets in dense population areas and/or to employ land operations inside Gaza. Most observers accept that the buffer zone strategy alone will not defeat the threat. A CLEAR reassessment of Israeli policies is in order. More funds are needed to develop a defensive response, but that will take some time. The key operators of the Kassam attacks have to be identified and eliminated. Asking the Egyptians to intervene and to impress upon the Palestinians the extent of Israel's exasperation merely further undermines Jerusalem's deterrence since such pleas from a foreign country underscore our helplessness. It is also possible that Prime Minister Ariel Sharon may have decided to wait until more Jewish blood is spilled to warrant a stronger riposte. Elections at home and among the Palestinians obviously complicate the strategic equation. In the meantime, the emerging policy of creating a buffer zone in northern Gaza can only be effective if it is systematically enforced, and the Kassam launching areas really do become killing zones subjected to Israeli fire. Israel must also decide whether it is ready to expand the killing zones. What happens when the enemy extends the range of their rockets and launches them from urban areas further removed from the Israeli border? Are we ready to push the Palestinian population beyond the Kassams' range? International law definitely permits military response, including artillery shelling, aimed at the sources of fire, even in urban areas. Creating a refugee wave - by the threat of force in urban areas and by precise fire on empty buildings - would exact a high price for Kassam attacks, which might result in some Palestinian restraint. Palestinian dependency on Israel for the supply of electricity and water, as well as for access to our labor market, should be capitalized on to impress upon the Palestinians that reciprocity is the name of the game. Israel has no obligation whatsoever to be nice to the Palestinians if they are indiscriminately killing, or trying to kill, civilians and damaging, or trying to damage, vital infrastructure installations. Israeli policy should be to clearly signal that life on the Palestinian side of the border will be invariably affected by Palestinian violence intent on deteriorating the quality of life on Israel's side of the border. Neither we ourselves nor the world at large should buy the idea that most Palestinians are peace-loving, interested only in carrying on with their daily lives, and the victims of a few radicals who perpetrate terrorist acts against Israel. The massive support for Hamas in the recent municipal elections and the anticipated support they are projected to have in the upcoming national elections plainly indicates that Hamas's advocacy of destroying the Jewish state is not the preference of a small, uncontrolled minority as Palestinian propagandists claim. Indeed, all polls show high levels of support among Palestinians for killing Israelis. Fortunately, Israel can somewhat influence Palestinian preferences by wearing them out. Indeed, the intifada has lost some of its popularity due to Palestinian fatigue. Sadly, the naked truth is that only greater Palestinian suffering stands a chance of influencing their "learning curve" and lowering the number of Kassam attacks. The author is professor of political science at Bar-Ilan University and the director of the Begin-Sadat Center for Strategic Studies.