I'm reasonably certain that the fundamental goal of US Middle East policy is destabilization.

For example, the amount of saber-rattling US politicisns do in regard to Iran appears to be inversely proportional to the actual threat it poses. When the hard-liners are in power, the US generally backs off and focuses elsewhere, but then when reformists gain power and it starts looking like Iran might settle down and stabilize a bit, suddenly the US government starts up another hue and cry about the threat it supposedly poses, which gives the hard-liners just the angle they need to take power again, at which point the US stops focusing on Iran again.

I presume it's a hegemonic strategy. Stable and well-governed Middle East nations, with the sort of wealth they possess, could pose a threat to western hegemony, while unstable and poorly governed ones can't.