we will seize the fields before allowing a worldwide depression to occur.
Depends on who is in charge, here. Also it will be a risky gamble if OPEC is in collusion at the time with nuclear capable nations who are both paranoid and have itchy trigger fingers. Russia comes to mind, but there are others with a big enough stake in mid-east oil.
I also wouldn't put it past a savvy President who might have the cojones to use the crisis to force Congress into mandating oil exploration both offshore and in Alaska.