Israel crossed a serious line and I believe they did so to get the US into a full fledged war.
I don't care how evil the opponent supposedly is, or how bloodthirsty the battle, or how valuable the target, you never-never-ever-ever strike an embassy.
Pretty sancrosanct reason: Diplomats end conflicts. You strike an embassy, you're literally killing the mechanism for any future negotiation. Another reason: While the embassy is the sovereign soil of that building's ambassador nation, you're striking another power's soil in the radius all directions surrounding the compound.
The fact the world is not outraged by this is quite telling.