Treasures of Aht Urhgan Mission 3
President Salaheem
Talk to Naja Salaheem at the end of Mission 2, and you'll receive a PSC Wildcat Badge, which gives you access to begin Assault and participate in Beseiged. You'll also gain access to the Mog Lockers.
Head to the Commission Agency (Aht Urhgan Whitegate, K-10) and talk to Rytaal to gain access to Assault. Then, head over to the entrance to the Mog House and talk to Fubruhn (F-11).
You'll need to wait until the next Earth day (after midnight Japan time) to complete the mission.