First off, there is a proposal for an additional $14.5 billion in US aid to Israel in the current budget, which is directly tied to the current war in Gaza. That amount of money may well be existential. Also, we have not established that the loss of even just the $3 billion a year is not an existential matter. You have claimed that, and it may be so, be we don’t know that for certain. A 12% cut in the military budget could be catastrophic in the middle of an active war.
Secondly several people here have noted before that US military aid is essentially in the form of vouchers that are used to buy US made armaments. That is true, but it isn’t like Israel is the only possible customer out there. We could send Israel’s money to Ukraine or put out a call for proposals to all of the current combatants around the world and say that $3 billion is available to anyone who is willing to do what the US wants as opposed to getting all lippy about it.
Regarding using the money as a lever - we have been pouring money into Israel for decades, and that doesn’t seem to be working in driving the current US agenda. So maybe removing the money will do better? We won’t know if we don’t try.
And third, I did mention the carriers in the Med, not the 5th Fleet for the exact reason that the Eisenhower is currently specifically parked off the coast of Israel because of the current was in Gaza. Does the removal of that carrier lead to Hezbollah or other actors in the region taking bolder actions against Israel? Maybe it does, and that certainly does sound like a possible existential threat to Israel. Perhaps enough to make the people of Israel take action now.
How does this serve US interests? Currently, the US government is officially in favor of a two-state solution. The Israeli Prime Minister just said he doesn’t support that. It seems to me that making the Israeli government change their anti-two-state position or change the government entirely would serve US interests for the future of that piece of real estate.
Finally, and just to be really blunt here, Israel facing an existential crisis is not an existential crisis for the US - or at least it really doesn’t have to be if certain political forces are ignored. The US uses financial and military pressure to change foreign governments all of the time, and Israel really shouldn’t be special in that regard. And in this case, it is super easy - we literally have to do nothing.
And to be even more blunt, at a certain level it really doesn’t matter to the US who lives in or governs the land currently within the borders of Israel. And please, that is not an invitation to reopen the discussion of Israel’s value to the US. I’ll concede all of them, but none of them are essential to the US. Or to put it in your terms, the continued existence of Israel is not an existential matter to the US. I would prefer Israel be part of a two-state solution in that region, but at a certain point, the US could decide that it isn’t worth the investment to continue propping up Israel.