On the third mission, "Lord Of War", one of the objectives is to provide cover fire for your downed ally. This can be difficult with the frequent RPG fire you will draw from the enemy infantry. However, if you use your missiles to destroy the surrounding buildings where most of the infantry spawn, you will have a much easier time. You can easily shoot the enemies with the FLIR view as they spawn, before they have a chance to move. This is also useful because many of the RPG soldiers fire from the rooftops. Clearing out the buildings will significantly decrease the amount of RPG shots taken at you.