Israel has been under siege from missiles and rockets day in, day out ever since it withdrew from Gaza on September 12, 2005. Under siege without let-up: in Sderot and Ashkelon and in the kibbutzim and small villages around them. Sometimes, often enough, these trajectiles hit; more often they miss. But it is only time before the Palestinians will be able to target their weapons with deadly precision...and at longer range. Remember, Israel is a tiny country, wedged in between the sea and the great swath of hostile Arab territories. Tel Aviv and Jerusalem are insecurely within easy range of the land the peace processors have set aside in their imaginations for a Palestinian state. There are plenty of intra-Palestinian obstacles to a functioning Palestine. But there will not be a Palestine of any sort unless the mayhem from Gaza is brought to an end.Imagine the United States tolerating a situation in which there is relentless bombardment from across its border, and the regime there in power not only tolerates it but facilitates it, not only facilitates it but makes clear that it is a picture of the Israeli future. Not only the United States, but any and all governments, would respond and respond forcefully, more forcefully than Israel had responded. Nerves jangle constantly in Sderot and Ashkelon, an ancient (and exquisite) seaport which is also home to the largest desalination plant in the world which itself produces drinkable water at the lowest price in the world. Families have left the area, and there is a plan to send children from Sderot here, there, everywhere. These are not facts with which Israel can live.And so a few days ago and with palpable reluctance, Ehud Barak, minister of defense, imposed an interdict on the delivery of fuels to the Strip, especially gasoline. What other targeted government would allow supplies to cross its frontiers to its declared enemy, its ferociously declared enemy, and an enemy governed by Hamas which has sworn itself to the eradication of Israel? This may be a rhetorical question. But it beggars belief that people of good will -- or supposed good will -- should doubt its salience. In any case, the UN which is always declaring emergency in Gaza, did so again. And, frankly, I took comfort in Ehud Olmert's remark: "let them walk." The Geneva Convention has not established a right to drive during war-time. And the Palestinians have not even pretended that their rocketry is other than a war tactic.Almost as quickly as the Israeli closure began, the attacks on Israel's territory slowed. But they have slowed before. This is no game. Israel will not let it be a game once again.