The player must fight through several ambushes while trying to get to the extraction point. Beware, there will be many Riot shield troops in this level, and they can only be defeated by explosives, careful shots to an exposed arm or toe, or flanking them (which is a dangerous tactic on this level).
Perhaps the most effective way to beat this mission on Veteran is to steal a riot shield from one of the first three enemies the player will trigger to spawn. Swap the shield with your shotgun and be sure to keep the LMG that you spawn with. The player should pick up the shield and progress through the level slowly, being very careful that none of the enemies get behind the player. The riot shield will absorb all enemy fire from the front. It will also take one melee to kill regular infantry and only two melees to kill riot shield infantry. When the player gets to the last wave of enemies (which spawn on the lower level), he should carefully throw some flashbangs and grenades to take some of them down. Spraying with the M240 will also help. Finally, the player should retreat and let the riot shield enemies come to him. Melee them all and complete the mission.