Highway of Death
After a good portion of the level, you'll be tasked with taking out some mortar strike positions near the blue building at 600m for the second time. After taking them out, as part of the story, a suicide truck will spawn and begin driving towards you.
You will need to use your sniper and compensate for wind and distance to take out the driver. This will require two bullet to hit the windshield to destroy the protection, and then a final shot for the driver.
Reload the last checkpoint if you miss too many shots.
Possible on any difficulty, but recruit is probably recommended to make it as easy as possible.