USS John S. McCain (DDG-56) is an Arleigh Burke-class destroyer currently in the service of the United States Navy. She is part of the Destroyer Squadron 23 within the Third Fleet, and has her homeport at Naval Station Everett in Everett, Washington.

The Arleigh Burke class of guided-missile destroyers (DDGs) is a United States Navy class of destroyer centered around the Aegis Combat System and the SPY-1D multi-function passive electronically scanned array radar. The class is named for Admiral Arleigh Burke, an American destroyer officer in World War II and later Chief of Naval Operations. With an overall length of 505 to 509.5 feet, displacement ranging from 8,300 to 9,700 tons, and weaponry including over 90 missiles, the Arleigh Burke-class destroyers are larger and more heavily armed than many previous classes of guided-missile cruisers.