The Iron Curtain Defense System is the most impenetrable defensive system in the Kingdom. Much like the Sunshine Pastures Exclusion Zone it utilizes a variety of air and ground based weaponry to create a defensive shield around the top of the Ivykeep where the King resides. Unlike Sunshine Pastures, there is no known override key. The curtain can only be deactivated from the inside, through a process presumably known only to the King and close advisors.