NAK Altis Invade and Annex NAK Invade and Annex is a cooperative Arma mission where NATO forces complete missions, against CSAT and various Independent forces. Missions are generally classified as main missions or side missions. Main missions will have one or more sub-tasks that must be completed, in order for the main mission, to be complete. Side missions normally have a single task that must be completed. To help complete the missions, NATO forces have a virtual arsenal available to equip the soldiers and have a large selection of vehicles to choose from. Remember this is a cooperative mission, for the most fun you want to work with other players, and for that, communication is key.