Not only that, but I can't really think off of the top of my head any examples in which violence has succeeded in fighting injustice (in my personal opinion, however, calling what is happening an injustice is going too far. Israel is just defending itself - if the Arabs had never attacked Israel, they wouldn't be in this mess nowadays). It is only through peaceful tactics, such as those by Ghandi and MLK, through which any lasting changes have been made.
As Ghandi said, if everyone lived by the rule "an eye for an eye," the whole world would be blind.
Of course, prudent self-defense is always justified.