It would be only just if the Palestinians would get their own state after this.
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The current situation is like somebody commits a murder. Then the community rounds up a posse and goes out to kill the murderer. Then kill the murder's family, their neighbors, the residents of the next neighborhood over, raze the neighborhoods and then take all the land for themselves.
Justice means penalizing the guilty parties, not everyone in their geographical/social group. Your definition of Justice is leaky.
A singular terrorist event is not the same as an multi-decade occupation, on-going theft of land, discrimination, annexation plans, and - not least - a 2 year long genocide of tens of thousands of civilians.
So, no, that isn't what Hamas did.
But, and apologies if this hurts, none of that, absolutely none of that, justifies what has taken place since.
There is no place in this world for genocide. Particularly from a country that preaches "never again".
Nothing you can say will change my opinion on that.
Israel has really fucked up. It destroyed Gaza, yes. But in so doing destroyed it's reputation and standing for at least a generation.