Tom Clancy's H.A.W.X. 2

This is a story related trophy, however it also requires you to complete the mission on Expert difficulty. This is the nineteenth mission. This trophy is not missable, meaning after you complete the game on Recruit, you can replay this one level using the Mission Replay option, and ensuring you select the Expert difficulty. It is not too hard a mission, it involves dogfighting against enemy planes whilst keeping enemy ground targets away from the place you are protecting.

If you are having trouble with this mission, it can be completed in online co-op story or online co-op mission mode (with up to 3 online players helping you). Thanks to Blessorship for confirming this.