U.S. Fleet Activities Yokosuka, or Commander, Fleet Activities Yokosuka is a United States Navy base, in Yokosuka, Japan. Its mission is to maintain and operate base facilities for the logistic, recreational, administrative support and service of the U.S. Naval Forces Japan, U.S. 7th Fleet and other operating forces assigned in the Western Pacific. CFAY is the largest strategically important U.S. Naval installation in the western Pacific. As of August 2011^[update], it is commanded by Captain David Owen.

Fleet Activities Yokosuka comprises 2.3 km² (568 acres) and is located at the entrance of Tokyo Bay, 65 km (40 mi) south of Tokyo and approximately 30 km (20 mi) south of Yokohama on the Miura Peninsula in the Kantō region of the Pacific Coast in Central Honshū, Japan.

The 55 tenant commands which make up this installation support U.S. Navy Pacific operating forces, including principal afloat elements of the United States Seventh Fleet, including the only permanently forward-deployed aircraft carrier, USS George Washington (CVN-73), the group she heads, Carrier Strike Group Five, and Destroyer Squadron 15.