I don't think there is a line for Israel. They would probably try to find a way to support and justify Israel if they used a nuke. Genocide is nothing new to US, they are used to supporting it.
spoiler, no matter what these assholes do, the US wont give a shit. Isntrael is basically an unsinkable aircraft carrier to fuck the middle east up, as long as the US breathes, so will Isntrael.
Conclusively, nuking the US is the only correct course of action.