Defiance does not follow the same storyline as Call of Duty: Modern Warfare 3. Like the previous Nintendo DS Call 🔑 of Duty games, the storyline serves as a "companion narrative" to the console and PC versions.

The game opens with the 🔑 U.S. National Guard force training in Alaska at the time of the Russians invasion that takes place halfway through Call 🔑 of Duty: Modern Warfare 2. The National Guard works in conjunction with the British SFSG cross-training in the United States 🔑 to resist the Russians, including holding the town of Wilton against the Russians, and securing the Trans-Alaska Pipeline System from 🔑 capture.

The final part of the game takes place in Baltimore, where the National Guard and SFSG reclaim Baltimore/Washington International Thurgood 🔑 Marshall Airport taken by the Russian forces, and fight through the Baltimore seaport and learn that the Russians have moved 🔑 a WMD into the U.S., and are moving the weapon to a combat zone. The teams race through the port, 🔑 fighting their way aboard a cargo ship where the Russians are offloading the weapon. The National Guard team makes it 🔑 to the deck of the cargo vessel just as a Russian Hind helicopter carrying the weapon takes off. The teams 🔑 manage to bring down the helicopter with an RPG, and the game ends as the player's C.O. states, "Now the 🔑 real fight begins", referring to World War III in Modern Warfare 3.

The game received mixed reviews. Official Nintendo Magazine's Chris 🔑 Scullion states that the game was "Not without its flaws but an impressive shooter given the limitations of the hardware."[4] 🔑 James Dawson of Nintendo World Report wrote that "Call of Duty: Modern Warfare 3: Defiance isn't going to win any 🔑 awards, but as a DS port of a popular franchise, it does a decent job making the experience portable".[5]