See Operation True Heirs for more info.
This achievement will come from finishing all the missions in Saudi Arabia. The final mission in Saudi Arabia is "Intercept Shaheed and Recover Missles". This mission culminates with two different boss fights. Once you get to the checkpoint in order to make the jump on the convoy, you will have to fight Shaheed's second-in-command. This is a fairly straight-forward fight, in which you will have to deal with the rushing soldiers along with the leader. Start off by picking off the soldiers, as they will be rushing towards you in order to get you out of cover. Once taken care of, you should only have to deal with the mini boss. He will be using an Assault Rifle, that while it can deal some decent damage to you, is not too accurate, considering that he's on the bridge with a bit distance between you both. Chain Shot is your best option here, but using an Assault Rifle during the cool down period is a good idea as well. Stay very close to cover, and wait it out. The boss will always attempt to attack you, but he will always stay on the bridge, so don't worry about being rushed.
Once you've finished him off, you will need to take care of the Stryker Assault vehicle, which is even easier than the last fight. Again, pick off all the nearby enemies that will try to rush you. Once you do, drop down from the bridge via the nearby ladder, and begin to close the distance from the Stryker. Along the way, you will see several RPG's lying around. Very quickly, sprint to each one, and use them against the Stryker to damage it. Take your time though, and be sure that your Endurance is fully restored before exposing yourself again.