Popular Mechanics:
The U.S. Navy, reacting to an increasingly active Russian Navy, will reactive the Second Fleet. The Second Fleet was historically responsible for the East Coast and the Atlantic Ocean ranging out to halfway between North America and Europe.
The fleet will likely coordinate a response to Russian cruise missile submarines operating near the continental United States. The U.S. Navy is organized around several numbered fleets, each with a particular geographical area of responsibility.
The Seventh Fleet, for example, is based out of Japan and is responsible for the Western Pacific, while the Sixth Fleet is based out of Naples, Italy and controls American naval forces in the North Sea, North Atlantic, South Atlantic, and Mediterranean.
