The U.S. is an empire, and Israel is it's largest military outpost in the Middle East. Israel also gives the U.S. deniability: Israel can do things that align with U.S. interests (e.g., various attacks on Iran), but the U.S. doesn't risk blowback to the same degree it would if the U.S. pulled the trigger itself.

This is why the U.S. generally supports everything Israel does, only pulling the leash when Israel's actions start to get inconvenient.

The late state empire problem the U.S. is facing now is that it's stocked its government with too many true believers to recognize this dynamic. They just support Israel full stop now, no matter what Israel does, no matter if (as Democrats just saw) it costs your party an election. Trump is surrounded by these true believers, but doesn't give a shit about anything himself and only understands self-interest, so where we go from here is up in the air.