Defensive Perimeter is the first mission in Airforce Delta Storm.
Unless you are playing a new game plus, you will have to use the starting plane, the slow A-7 Corsair II, for this mission. There are three planes in the sky and you have to shoot only one of them down. There are several hovercraft L.C.A.C.s carrying M2A2 I.F.V.s and approaching the shore. If you destroy an L.C.A.C. before it reaches the shore, the tank it was carrying will be destroyed as well. If an L.C.A.C. reaches the shore however, the tank it was carrying will get off it and begin shooting bullets at you. If you don't destroy the L.P.D. I.Rogov ships within approximately 2 minutes and 54 seconds, a second wave of L.C.A.C.s will be deployed and you'll have to take those out as well. The mission is completed once all targets are destroyed/shot down.
- Destroy/Shoot down all targets.
The reward for this mission is 10,000 credits plus a variable amount depending on the number of enemies taken out. More credits can be earned from shooting down the planes with bullets. The F-5E Tiger II and MiG-21bis Fishbed are also unlocked in the shop for 90,000 credits and 65,000 credits respectively. The Battle of Castalia Sea is also unlocked.
We have received a warning from the Lodey Coast Guard squadron. United Forces landing troops are converging and about to attempt a landing. You must intercept and destroy the landing party. Over and out.
Delta Leader: (When mission is selected on the map) An enemy landing party has been spotted approaching the Lodey Coast. Our mission is to destroy the landing party.
Narrator: Alexxy Peninsula, December, 20X6. Allied Forces 11th Aerial Fleet.
Delta Leader: This is Delta Leader to all fighters. It seems that enemy landing troops are about to take the beachhead. This mission is to eliminate the landing troops. I repeat: aim for the landing craft. Keep the troops from taking the beachhead. All fighters deploy into attack formation!
Delta 2: Roger!
Delta 3?: Roger!
[pre-mission cutscene ends]
Delta 2?: Enemy landing party approaching. [if the L.C.A.C.s reach the shore] Enemy landing party has reached the shore. Eliminate them immediately. [if the L.P.D. I.Rogovs are not destroyed within approximately 2 minutes and 54 seconds into the mission] 2nd wave of enemy landing party closing. [again, if these L.C.A.C.s reach the shore] Enemy landing party has reached the shore. Eliminate them immediately.
[mission ends once all targets are destroyed]
Delta Leader: This is Delta Leader to Control. Mission accomplished. Now returning to base.
Control: This is Control. Roger that.
Narrator: It is the year 20X1. Food supply problems have reached a critical limit. The world is divided into two halves: those who can eat, and those who cannot. Advances in genetics mean that even the worst diseases can be cured, but the earth has not been turned into the Garden of Eden that was promised. Instead, war rages on as they always have. Here, on the Alexxy Peninsula, the Allied Forces and the United Forces come to a new twist in their long struggle... [says title of game]
[post-mission cutscene ends]
Main article: Soundtrack for Defensive Perimeter and Final mission