diff --git a/mods/ra/maps/fort-lonestar/fort-lonestar.lua b/mods/ra/maps/fort-lonestar/fort-lonestar.lua
index 5a8ff0f330..63d50e81d5 100644
--- a/mods/ra/maps/fort-lonestar/fort-lonestar.lua
+++ b/mods/ra/maps/fort-lonestar/fort-lonestar.lua
@@ -29,7 +29,7 @@ Waves =
 	{ delay = 1500, units = { Infantry, Infantry, Infantry, Infantry, Infantry, Infantry, Infantry, Infantry, Infantry, Boss } }
 }
 
-SendUnits = function(entryCell, unitTypes, targetCell)
+SendUnits = function(entryCell, unitTypes, targetCell, extraData)
 	Reinforcements.Reinforce(soviets, unitTypes, { entryCell }, 40, function(a)
 		if not a.HasProperty("AttackMove") then
 			Trigger.OnIdle(a, function(a)
@@ -45,6 +45,10 @@ SendUnits = function(entryCell, unitTypes, targetCell)
 				a.Hunt()
 			end
 		end)
+
+		if extraData == "IronCurtain" then
+			a.GrantTimedUpgrade("invulnerability", DateTime.Seconds(25))
+		end
 	end)
 end
 
@@ -60,6 +64,15 @@ SendWave = function()
 			SendUnits(entry, units, target)
 		end)
 
+		if wave.ironUnits then
+			Utils.Do(wave.ironUnits, function(units)
+				local entry = Utils.Random(SovietEntryPoints).Location
+				local target = Utils.Random(SpawnPoints).Location
+
+				SendUnits(entry, units, target, "IronCurtain")
+			end)
+		end
+
 		Utils.Do(players, function(player)
 			Media.PlaySpeechNotification(player, "EnemyUnitsApproaching")
 		end)
diff --git a/mods/ra/maps/fort-lonestar/map.yaml b/mods/ra/maps/fort-lonestar/map.yaml
index 6da83a5a59..fc105a1280 100644
--- a/mods/ra/maps/fort-lonestar/map.yaml
+++ b/mods/ra/maps/fort-lonestar/map.yaml
@@ -524,6 +524,8 @@ Rules:
 			Type: LightningStrike
 		LuaScript:
 			Scripts: fort-lonestar.lua
+		ScriptUpgradesCache:
+			Upgrades: invulnerability
 	FORTCRATE:
 		Inherits: ^Crate
 		SupportPowerCrateAction@parabombs: