The Battle of the Rybachiy Naval Base was the final battle of the Petropavlovsk Campaign. The capture of a nuclear submarine by Task Force 141 personnel caused a nuclear missile to be launched as an EMP to disable Russian and American equipment on the US Eastern Coast, turning the tide of the Battle of Washington D.C..
After freeing John Price from the Petropavlovsk Gulag, Price proposed to Shepherd taking control of a nuclear submarine and using its nukes to defeat the Russians in America, hopefully ending the war. Shepherd disagreed with this plan, considering it too drastic; however, Captain Price and Task Force 141 personnel supporting him helped assist in attacking the Rybackiy Naval Base, interested in the possibility of ending World War III quickly.
John Price and Gary "Roach" Sanderson worked their way past various Russian patrols and vehicles in order to approach the naval base. As they approach, they find a small village. Roach is ordered to use a predator drone, but the drone is destroyed by an active SAM site. Price and Roach slide down into the village, with Ghost and several other Task Force 141 personnel arriving as backup. Soap provides another predator drone to use for attacking the naval base. When this drone is used, the team moves close to the docked submarine, with Price boarding it in an attempt to take control of the vessel. While Price was being protected by Task Force 141 personnel, Price opened the silo doors and launched a nuclear missile towards Washington D.C.. The remaining Russian units in the naval base were neutralized and the submarine and naval base were captured by the United States.
The North American Defense Command in Colorado Springs detected the missile launch; they predicted that the missile would strike Washington D.C., disabling all electronic equipment there. Shepherd was granted a "blank check" to hunt down Vladimir Makarov for starting World War III, in order to prevent any further interference Makarov may take against the United States. Sat1 provided a video feed of the nuclear missile until the missile exploded, destroying the ISS and killing Sat1. The detonation disabled Russian and american equipment on the US Eastern Coast, halting the invasion.