The structure of the United States Navy consists of four main bodies: the Office of the Secretary of the Navy, the Office of the Chief of Naval Operations, the operating forces (described below), and the Shore Establishment.
The Office of the Chief of Naval Operations (OpNav) includes the Chief of Naval Operations, the Vice Chief of Naval Operations, the Deputy Chiefs of Naval Operations, the Assistant Chiefs of Naval Operations, the Chief of Legislative Affairs, the Director of Naval Nuclear Propulsion, the Master Chief Petty Officer of the Navy, and other members of the Navy or Marines or civilians in the Department of the Navy assigned or detailed to the Office.
As of June 2008, there was a DCNO Manpower and Personnel/Chief of Naval Personnel (N1), the Deputy Chief of Naval Operations for Information Dominance (N2/N6), (established October 2009), DCNO Plans, Policy, and Operations (N3/N5), DCNO Fleet Readiness and Logistics (N4), DCNO Warfare Requirements and Programmes (N6/N7), and DCNO Resources, Requirements and Assessments (N8). In addition there was a Director of T&E and Operational Requirements, Surgeon General of the Navy, Chief of Naval Reserves, Chief of Oceanography, and Chief of Chaplains of the Navy.
The operating forces consists of nine components:
Fleets in the United States Navy take on the role of force provider; they do not carry out military operations independently, rather they train and maintain naval units that will subsequently be provided to the naval forces component of each Unified Combatant Command. While not widely publicized, groups of ships departing U.S. waters for operational missions gain a Task force type designation, almost always with the Second or Third Fleets. On entry into another numbered fleet's area of responsibility, they are redesignated as a task group from that fleet. For example, a carrier task group departing the Eastern Seaboard for the Mediterranean might start out as Task Group 20.1; on crossing the mid-Atlantic boundary between Fleet Forces Command and United States Naval Forces Europe - Naval Forces Africa, it might become ('inchop') Task Group 60.1.
The United States Navy currently has seven active numbered fleets. Various other fleets have existed, but are not currently active.
|Numbered Fleet||Status||Parent Command||Geographic Region||Notes|
|1st Fleet||Inactive||Pacific Fleet||N/A||The First Fleet existed after World War II from 1947, but was redesignated Third Fleet in early 1973. The United States Coast Guard is sometimes believed to act as the First Fleet in wartime; however, the United States has never officially used this reference and it is informal at best.|
|2nd Fleet||Active||Fleet Forces Command||Western North Atlantic Ocean||The Second Fleet was redesignated from the Second Task Fleet in 1950 as part of the then-United States Atlantic Fleet. It was deactivated in 2011, then reactivated on 4 May 2018.|
|3rd Fleet||Active||Pacific Fleet||Eastern Pacific Ocean||The Third Fleet was redesignated from First Fleet in early 1973.|
|4th Fleet||Active||Naval Forces Southern Command||Southern Atlantic Ocean||The Fourth Fleet was active during World War II and deactivated in 1950 when its responsibilities passed to Second Fleet. It was reactivated in 2008.|
|5th Fleet||Active||Naval Forces Central Command||Mediterranean Sea & Persian Gulf||The Fifth Fleet was deactivated in 1947 after serving during World War II. It was reactivated in 1995 to assume responsibilities in the Persian Gulf previously assigned to Seventh Fleet.|
|6th Fleet||Active||Naval Forces Europe||Eastern North Atlantic Ocean||The Sixth Fleet was redesignated from Sixth Task Fleet in 1950 and has been continuously active in the Mediterranean since 1950.|
|7th Fleet||Active||Pacific Fleet||Western Pacific Ocean & Indian Ocean||The Seventh Fleet was activated in 1943, redesignated Naval Forces Western Pacific in 1947, Seventh Task Fleet in 1949 and to its current designation in 1950.|
|8th Fleet||Inactive||Atlantic Fleet||N/A||The Eighth Fleet was established in 1943 from Northwest African Force. It operated in the Mediterranean Sea during World War II, with its forces briefly reassigned to Twelfth Fleet. From 1946-47 served as the heavy striking arm of the United States Atlantic Fleet before being redesignated Second Task Fleet and later Second Fleet.|
|9th Fleet||Inactive||Atlantic and Pacific||N/A||Before 15 March 1943, Commander, U.S. Naval Forces Europe served as Commander Task Force 99, of the 9th Fleet, which was under the direct command of Admiral King. On 15 March 1943, TF 99 was redesignated TF 92. On 15 August, the 9th Fleet was redesignated 11th Fleet, still under the direct command of Admiral King, and TF 92 was redesignated TF 112. Task Forces in the 90s series have been used since World War II. In 1945, under Admiral Nimitz, CINCPOA, as Commander Ninth Fleet, Task Forces 90-92 formed the North Pacific Force, and the higher numbers were used for Strategic Air Force, POA, and local defences (Marshals-Gilberts Force, Hawaiian Sea Frontier, etc.). Naval Forces Far East used 90-series task forces in Korea.|
|10th Fleet||Active||Fleet Cyber Command||Global||The Tenth Fleet was active during World War II and reactivated in 2010 for assignment to Fleet Cyber Command.|
|11th Fleet||Inactive||Pacific Fleet and Atlantic Fleet||N/A||Redesignated on 15 August 1943 from 9th Fleet and subsequently transferred to Atlantic Fleet|
|12th Fleet||Inactive||Naval Forces Europe||N/A||The Twelfth Fleet was active in European waters during World War II. It was redesignated United States Naval Forces Mediterranean in 1946, which later became Sixth Task Fleet.|
Additional numbered fleets have existed; for a period after World War II, the Sixteenth and Nineteenth Fleets were assigned as the reserve elements for Atlantic and Pacific Fleets.
The organization of the Navy has changed incrementally over time. During World War II administrative organization for many ship types included divisions, for example Battleship Divisions (abbreviated BatDivs), Cruiser Divisions, Destroyer Divisions, or Escort Divisions (CortDivs, also rendered ComCortDiv for Commander, Escort Division), usually composed of two ships, often members of the same class. These made up squadrons (e.g. Battle Squadron, Cruiser Squadron, Escort Squadron (CortRon) etc.) of several divisions. Yet the exigencies of World War II forced the creation of the task force system where ships no longer fought solely as part of same-type divisions or squadrons. This was gradually reflected in administrative arrangements; by the 1970s, formations such as Cruiser-Destroyer Groups (CruDesGrus) came into existence.
The Navy is currently organized as such:
The Navy maintains several "Naval Forces Commands" which operate naval shore facilities and serve as liaison units to local ground forces of the Air Force and Army. Such commands are answerable to a Fleet Commander as the shore protector component of the afloat command. In times of war, Commander Naval Forces Korea becomes a Task Force (Task Force 78) of the United States Seventh Fleet. Other Naval Force Commands may similarly augment to become number fleet task forces.
Per 10 U.S. Code § 5001 (a) (2), § 5061 Introduction, § 5061 (4), and § 5063 (a): the United States Marine Corps, is (1) a separate branch of the naval service from the U.S. Navy; (2) the Department of the Navy and the U.S. Navy are distinct legal entities; (3) is, along with the U.S. Navy (and U.S. Coast Guard, when assigned) a component of the Department of the Navy; and (4) a branch of U.S. military service, separate from the U.S. Navy, within the Department of the Navy. Furthermore, per 10 U.S. Code § 5001 (a) (1), § 5061 (4), § 5062 (a): (1) the United States Navy does not include the United States Marine Corps (2); the U.S. Marine Corps is a separate component service, from either the U.S. Navy or the U.S. Coast Guard within the Department of the Navy; and (3) the U.S. Marine Corps is not a component of the U.S. Navy.[clarification needed]
In 1834, the United States Marine Corps (USMC) came under the Department of the Navy. Historically, the United States Navy has enjoyed a unique relationship with the Marines, partly because they both specialize in seaborne operations. At the highest level of civilian organization, the USMC is part of the Department of the Navy and reports to the Secretary of the Navy. However, it is considered to be a distinct, separate service branch and not a subset of the Navy; the highest ranking Marine officer, the Commandant of the Marine Corps, does not report to a Navy officer. Marine Corps Medal of Honor recipients are awarded the Navy variant, and Marines are eligible to receive the Navy Cross. The United States Naval Academy trains Marine Corps commissioned officers while prospective Navy officers undergo instruction by Marine NCO Drill Instructors at OCS. Naval Aviation includes Navy and Marine aviators, flight officers, and aircrew.
The relationship extends to the operational theater as well. As amphibious assault specialists, Marines often deploy on, and attack from, Navy vessels; while being transported on Navy ships, they must obey the orders of the captain of the vessel. Marine aviation tailhook squadrons train and operate alongside Navy squadrons, flying similar missions and often flying sorties together. Other types of Marine air squadrons operate from amphibious assault ships in support of Marine amphibious operations. Navy and Marine squadrons use the same NATOPS aviation manuals and procedures. The USMC does not train chaplains, hospital corpsmen or medical doctors; thus officers and enlisted sailors from the Navy fulfill these roles. They generally wear Marine uniforms that are emblazoned with Navy insignia and markings to distinguish themselves from Marines. Corpsmen and chaplains enjoy a great sense of camaraderie with the Marines due in part because they work closely with them and often are embedded with Marine units. They operate under the command of the Marine Corps under the auspices of the Fleet Marine Force, often called the "green side".
Because of the lack of full-scale amphibious operations in recent conflicts, there has been pressure to cut the "gator navy" below the two-regiment requirement of the Marines. This is a reduction from the programmatic goal of 2.5 Marine Expeditionary Brigades and actual structure of 2.07 MEB equivalents in 1999.
The relationship between the US Navy and US Marine Corps is also one of mutual respect, and that respect is manifested in various policies and procedural regulations. For example, per US Marine and Navy drill manuals, in a formation consisting of both Marine and Navy units, per MCO P5060.20, Marine Corps Drill and Ceremonies Manual, Paragraph 15001. "ARRANGEMENT OF UNITS IN FORMATION 1. In ceremonies involving the U.S. Marine Corps and U.S. Navy units, the Marine unit shall be on the right of line or head of the column. The senior line officer, regardless of service, functions as the commander of troops." (As this is a Department of Defense/Department of the Navy regulation, no further 10 U.S. Code authority, other than already cited above, is required for the Secretary of the Navy, who supervises both the U.S Navy, and the U.S. Marine Corps, as well as the U.S. Coast Guard whenever it is assigned to the Department of the Navy, to specify that the Marine Corps takes precedence over the Navy and Coast Guard in Naval formations, parades, and ceremonies. This same military precedence is specified in DoD Instruction 1005.8 and U.S. Navy Regulations, Chapter 10, Paragraph 1007.) This is a symbol of the special status and honor granted to US Marines, and is a unique aspect of the Navy-Marine relationship.
Although the Posse Comitatus Act, which prevents federal military personnel from acting in a law enforcement capacity, applies only to the Army and Air Force, Department of Defense rules effectively require the Navy and Marine Corps to act as if Posse Comitatus did apply, preventing them from enforcing Federal law. The United States Coast Guard fulfills this law enforcement role in naval operations. It provides Law Enforcement Detachments (LEDETs) to Navy vessels, where they perform arrests and other law enforcement duties during Navy boarding and interdiction missions. In times of war, or when directed by the President, the Coast Guard operates as a service in the Navy and is subject to the orders of the Secretary of the Navy until it is transferred back to the Department of Homeland Security. At other times, Coast Guard Port Security Units are sent overseas to guard the security of ports and other assets. The Coast Guard also jointly staffs the Navy's Naval Coastal Warfare Groups and Squadrons (the latter of which were known as Harbor Defense Commands until late-2004), which oversee defense efforts in foreign littoral combat and inshore areas. Additionally, Coast Guard and Navy vessels sometimes operate together in search and rescue operations.