Its no coincidence Putin pulled his forces back from the Ukraine border recently. These low prices coupled with the sanctions are killing their economy. Interesting point about the Saudis trying to hamstring our growth.
You are talking about reactions ... what caused the oil price plunge in the first place? Answer: yes, it is American intervention.
It could have been a corridinated release of Saudi oil reserves and ramp up of shale production, asked by the Eurozone to put pressure on Russia. And the massive slowdown of China’s economy did not help oil prices either.