Structure of the United States Navy 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 . Office of the Chief of Naval Operations . 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 ) , 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 . Operating forces . The operating forces consists of eight components : United States Fleet Forces Command , United States Pacific Fleet , United States Naval Forces Central Command , United States Naval Forces Southern Command , United States Naval Forces Europe , U . S . Fleet Cyber Command , United States Navy Reserve , United States Naval Special Warfare Command , and Operational Test and Evaluation Force ( OPTEVFOR ) . 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 entry into the Mediterranean , it might become ( ' inchop ' ) Task Group 60 . 1 . The United States Navy has six active numbered fleets . These six numbered fleets are grouped into operating forces : the U . S . Pacific Fleet ' s 3rd Fleet and 7th Fleet , Naval Forces Europe ' s 6th Fleet , Naval Forces Central Command ' s 5th Fleet , Fleet Cyber Command ' s 10th Fleet and Naval Forces Southern Command ' s 4th Fleet . 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 . Historical organization . 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 Division s ( abbreviated BatDivs ) , Cruiser Divisions , Destroyer Divisions , or Escort Divisions ( CortDivs ) , 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 United States First Fleet existed after the Second World War from 1947 at least , but it was redesignated Third Fleet in early 1973 . Other fleets , such as the 10th and 12th , were active during World War II , the 12th in European waters as part of United States Naval Forces Europe . The 2nd Fleet was disestablished in 2011 . The Shore Establishment . The following shore - based bureaus , commands and components are directly subordinate to the Chief of Naval Operations : " Relationships with other service branches . United States Marine Corps . 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 Brigade s 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 Marines and Sailors , Marines are to be present at the front ( in column ) and left ( on line ) , regardless of rank . This is a symbol of the special status and honor granted to US Marines , and is a unique aspect of the Navy - Marine relationship . United States Coast Guard . 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 Unit s 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 .