Hamas should absolutely be blamed for the brutal, barbaric murders of innocent people in Israel, specifically for the October 7 attacks, but others as well.
Israel should be blamed for perpetuating a genocide in Gaza.
Japan should be blamed for starting a war and then failing to end it, while they traded their people for better terms. So, yeah, they should be blamed for the number of deaths required to end it. Whether they should be blamed for Nagasaki and Hiroshima depends on whether you believe those were necessary to end the war. I think it's reasonable that Hiroshima could have ended it, had the US provided enough time for Japan to understand the damage. So, personally I think Nagasaki is on the US, but I get that opinions may differ. Hopefully we can all agree that it wasn't Italy's responsibility.
I think we are way past the number of deaths required to be useful in stopping another October 7th attack. At this point, it's about revenge, expansion, and ethnic cleaning. It's genocide and Israel is entirely, 100% responsible for it.