Derbent is the southernmost city in Russia, located southeast of the Caucasus Mountains. It is one of the oldest cities in Russia and features ancient fortifications, including a large fortress west of the city at the base of the mountains.
Derbent played a minor role in the events of the Ace Combat: Assault Horizon story campaign. The player must help the Russian Loyalists liberate the city from enemy rule and destroy the anti-air emplacements in Derbent's fortress.
In the Assault Horizon universe, the New Russian Federation took control of Derbent's gas and oil pipelines. The Russian Loyalists prioritized the recapture of Derbent in their initial counterattack during the war. The loyalist landing force unit, Tyuleni, coordinated its operation with Task Force 108, including Molot and Warwolf Squadrons. After they successfully captured Derbent's fortress, Andrei Markov attempted to decimate Derbent with a Trinity cruise missile; William Bishop intercepted and safely destroyed the missile above the city.