Daveed Gartenstein-Ross reminds us that if al Qaeda attacked the Saudi oil supply they could still seriously damage the US economy:
The kingdom relies on its Abqaiq facility to process two-thirds of its crude oil, and on two primary terminals (Ras Tanura and Ras al-Ju'aymah) to export its oil to the world. The economic impact of a successful attack on one of these targets would be tremendous: Gal Luft and Anne Korin of the Institute for the Analysis of Global Security estimate that, if a terrorist cell hijacked a plane and crashed it into either the Abqaiq or Ras Tanura facilities in a 9/11-style attack, it could "take up to 50% of Saudi oil off the market for at least six months and with it most of the world's spare capacity, sending oil prices through the ceiling."
The Dish 