Why are the US and Saudi Arabia allies?

[True Federalist (진정한 연방 주의자)]

Aramco, when was originally a way for the Americans and the Saudis to give the British a one fingered salute. Old habits die hard, but luckily for the Saudis the habit of Saudi-American friendship didn't die before the Iranians could replace the British as a mutual boogeyman.

[True Federalist (진정한 연방 주의자)]

Surprised "Inertia" and "Force of habit" haven't been listed because they're more explanatory reasons than anything else mentioned above.

We're allies with KSA because FDR was allies with ibn Saud 80 years ago.

Aramco, when was originally a way for the Americans and the Saudis to give the British a one fingered salute. Old habits die hard, but luckily for the Saudis the habit of Saudi-American friendship didn't die before the Iranians could replace the British as a mutual boogeyman.