Andrew Lawson has made some apropos videos that succinctly describe the situation of America regarding Israel.
Are those in Congress who sign letters that all but tell Israel it may do as it wishes without fear of the US acting against it, treasonous? To tell a tiny country that it may act with the full backing of the world's superpower invites irresponsible behavior. What would a schoolyard bully do if the police informed him that they would not restrain him no matter what he might do? This is why an attack on Iran by Israel is not to be dismissed as impossible, and assassinations of Iranians to induce military action in response is proceeding. The United States cannot say no to the Bully of the Middle East.