iran is run by a bunch of religious maniacs who unironically want to genocide all of the jews (everything they accuse israel of is a projection). they're an implacable enemy of the jews, and by extension the rest of the western world. no amount of concessions will satisfy them; any weakness shown will only encourage them.  israel isn't fundamentally imperialist or expansionist, despite whatever retards here think. democracies tend to be strongly isolationist and have a low tolerance for war casualties unless they're faced with an imminent foreign threat.  anyway the threat of a nuclear war between the us and russia is much more serious. and unlike iran, russia is not an implacable enemy run by religious fanatics. the russians can be reasoned with but for whatever reason the us would rather keep antagonizing them.
Tree Hugger