Yes, it's justified. They have been attacked repeatedly by the Palestinian-and NO, the Palestinians aren't doing it in self-defense. They have repeatedly stated their wish to annihilate all Jews because their 'god' tells them to do it. If they (the Palestinians) really wanted peace, they would have respected the Oslo accords, and they wouldn't have a mouse and a bee telling pre-school aged children that killing jews is okay and that all of Israel belongs to Muslims.
This whole thing: it's completely, one hundred percent a holy war waged by muslims since they think they're entitled not only to the Jewish state, but to the entire world. I shudder at the thought of what the world would look like if they got their way.