The Israeli Foreign Minister Tzipi Livni has said that air strikes in Gaza which have killed at least 155 people were justified by the "right of Israel to defend herself".
There is a difference between defence and revenge. This was not defence, it was revenge. And revenge just brings more revenge.
There is no defence that I know of against the small rocket attacks launched by Hamas, but luckily they are unguided, and although they do unfortunately kill and maim a few Israelis, strategically they are an irritant rather than a threat. Unfortunately the effect of the irritant is to provoke massive Israeli counter attacks, which hurt Palestinian civilians more than the fighters.
In short, the Hamas rockets cause more harm to Gaza than they do in Israel. When I ask Palestinian sympathisers why they keep up the provocation, the answer is
"The Israelis have robbed us of our country. What would you do if you had been robbed? Lie there quietly, or fight back?"
The image that I have is of Palestine on the ground, robbed and injured. Standing over him is an Israeli with a club. The Palestinian keeps kicking the Israeli on the shin, and each time he does it, he gets another massive beating from the club.
Both parties are locked into a vicious circle of revenge. It is possible to break out of this cycle.
In the end, violence is the problem, not the solution.