NAVAL STATION YOKOSUKA

OVERVIEW

Naval Station Yokosuka — formally Commander, Fleet Activities Yokosuka (CFAY) — is the largest United States Navy installation overseas and the homeport of the U.S. 7th Fleet, the Navy's largest forward-deployed numbered fleet. Sited at the mouth of Tokyo Bay on Japan's Miura Peninsula, the base hosts the only U.S. aircraft carrier permanently forward-deployed outside the United States, along with cruisers, destroyers, command ships, and supporting auxiliaries assigned to Carrier Strike Group 5 and Destroyer Squadron 15.

The installation traces its origins to the Imperial Japanese Navy's Yokosuka Naval Arsenal, founded in 1865, and was occupied by U.S. forces in September 1945 following Japan's surrender. Today the base supports approximately 27,000 U.S. military members, civilian employees, and family members, plus roughly 13,000 Japanese employees working under the Master Labor Contract program. CFAY is operated jointly with the Japan Maritime Self-Defense Force, which maintains its own headquarters and fleet activities adjacent to the U.S. piers — making Yokosuka one of the most operationally significant joint U.S.–allied installations in the Indo-Pacific theater.

KEY FACTS

• Largest U.S. Navy Base OverseasBy personnel and infrastructure footprint
• Forward-Deployed CarrierHomeport of the only forward-deployed U.S. aircraft carrier
• Original ConstructionImperial Japanese Navy yard founded 1865
• Strategic PositionMouth of Tokyo Bay, Miura Peninsula
• Host Nation WorkforceApproximately 13,000 Japanese Master Labor Contract employees

HISTORY

Yokosuka's naval heritage predates the United States Navy's presence by nearly a century. In 1865, the Tokugawa shogunate engaged French naval engineer Léonce Verny to build a modern naval arsenal at Yokosuka — the first heavy-industrial shipyard in Japan and the cradle of the Imperial Japanese Navy. By the early 20th century, Yokosuka was Japan's principal naval base, building battleships including IJN Mikasa, Yamashiro, and the carrier Hiryu, and serving as the homeport of the Combined Fleet's 1st Fleet through World War II.

Following Japan's surrender aboard USS Missouri in Tokyo Bay on September 2, 1945, U.S. Marines and Sailors of the 6th Marine Division and Task Force 31 occupied the Yokosuka naval district. The base was formally commissioned as a U.S. naval facility in 1946 and quickly became the principal logistical hub for U.S. naval operations during the Korean War, supporting Task Force 77 carrier operations off the Korean peninsula. Throughout the 1950s and 1960s, Yokosuka served as the rear-area maintenance and replenishment base for the 7th Fleet, with the fleet commander embarked aboard a series of command ships and amphibious flagships.

The defining transition for modern Yokosuka came in October 1973, when USS Midway shifted homeport from Alameda, California to Yokosuka — becoming the first U.S. aircraft carrier permanently forward-deployed outside the United States. The arrangement, governed by the U.S.–Japan Status of Forces Agreement and an exchange of diplomatic notes, established the forward-deployed naval forces (FDNF) construct that has anchored U.S. Pacific strategy for half a century. Midway flew the flag at Yokosuka for nineteen years and was succeeded by USS Independence in 1991, USS Kitty Hawk in 1998, USS George Washington in 2008 (the first nuclear-powered carrier homeported overseas), USS Ronald Reagan in 2015, and USS George Washington again in late 2024.

Beyond carrier operations, Yokosuka has been continuously developed as a four-pier naval base supporting the 7th Fleet's surface combatants, including Aegis cruisers and destroyers of Destroyer Squadron 15. The base hosts Ship Repair Facility–Japan Regional Maintenance Center, the only U.S. Navy industrial-grade ship repair facility forward-deployed in the Western Pacific, capable of dry-docking a Nimitz-class carrier. CFAY also operates the U.S. Naval Hospital Yokosuka, which serves the broader military community in the Kanto Plain region. The base's continued operation is governed by the bilateral U.S.–Japan Treaty of Mutual Cooperation and Security and the 1960 Status of Forces Agreement, which together form the foundation of the U.S.–Japan Alliance.

MAJOR COMMANDS & TENANT UNITS

• Commander, Fleet Activities Yokosuka (CFAY)
• U.S. 7th Fleet (Commander, Task Force 70)
• Carrier Strike Group 5
• Destroyer Squadron 15
• Ship Repair Facility–Japan Regional Maintenance Center (SRF-JRMC)
• U.S. Naval Hospital Yokosuka
• Forward-deployed naval forces (FDNF) of the United States

LOCATION & GEOGRAPHY

HOST NATION CONTEXT

Naval Station Yokosuka operates under the U.S.–Japan Treaty of Mutual Cooperation and Security (signed 1960) and the bilateral Status of Forces Agreement (SOFA) signed the same year. The treaty obligates the United States to assist in defense of territories under Japanese administration, and authorizes the U.S. to maintain land, air, and naval forces in and about Japan.

Day-to-day base operations involve close coordination with the Japan Maritime Self-Defense Force (JMSDF), which operates an adjacent fleet base from the same harbor, and with Yokosuka City and Kanagawa Prefecture authorities. Approximately 13,000 Japanese citizens are employed on base under the Master Labor Contract — including ship-repair workers at SRF-JRMC, security personnel, and base-support staff — making CFAY one of the largest single employers in the city.

U.S. military personnel and SOFA-status family members enter Japan with no-fee tourist or official passports and a SOFA stamp; civilian visitors require a standard Japanese visa or visa waiver and must be sponsored for base access.

NOTABLE EVENTS

1. 1865
   Imperial Yokosuka Yard

   Imperial Japanese Navy founds Yokosuka Naval Arsenal under French engineer Léonce Verny — origin of the modern shipyard.
2. 1945
   U.S. Occupation

   Following Japan's surrender on USS Missouri in Tokyo Bay, U.S. forces occupy Yokosuka. Naval base established under the Far East Command.
3. 1973
   Forward Deployment

   USS Midway becomes the first U.S. aircraft carrier permanently homeported overseas at Yokosuka — beginning of the modern forward-deployed naval forces era.
4. 2008
   Nuclear Carrier Era

   USS George Washington arrives as the first nuclear-powered aircraft carrier permanently forward-deployed to Yokosuka.

NEARBY BASES

FREQUENTLY ASKED QUESTIONS

SOURCES

• Wikipedia: United States Fleet Activities Yokosuka
• CNIC — Commander, Fleet Activities Yokosuka
• U.S. 7th Fleet
• U.S. Department of State — U.S.–Japan Relations