A blue-water navy is a maritime force capable of operating globally, essentially across the deep waters of open oceans. While definitions of what actually constitutes such a force vary, there is a requirement for the ability to exercise sea control at long range.
The term "blue-water navy" is a maritime geographical term in contrast with "brown-water navy" (littoral waters and near to shore) and "green-water navy" (near to shore and open oceans).
The Defense Counterintelligence and Security Agency of the United States has defined the blue-water navy as "a maritime force capable of sustained operation across the deep waters of open oceans. A blue-water navy allows a country to project power far from the home country and usually includes one or more aircraft carriers. Smaller blue-water navies are able to dispatch fewer vessels abroad for shorter periods of time."
Attributes
In public discourse, blue-water capability is identified with the operation of capital ships such as battleships, battlecruisers, aircraft carriers, and nuclear submarines. For instance, during the debate in the 1970s whether Australia should replace , a former chief of navy claimed that if Australia did not replace her last aircraft carrier, she "would no longer have a blue-water navy". In the end Australia did not buy a new carrier, but former Parliamentary defence advisor Gary Brown could still claim in 2004 that her navy remained "an effective blue-water force". The Soviet Navy towards the end of the Cold War is another example of a blue-water navy that had minimal carrier aviation, relying instead on submarines, missile-carrying surface ships, and long-range bombers based on land.
A blue-water navy implies force protection from underwater warfare, surface warfare, and aerial warfare threats and a sustainable logistic reach, allowing a persistent presence at long range. A hallmark of a true blue-water navy is the ability to conduct replenishment at sea (RAS), and the commissioning of underway replenishment ships is a strong sign of a navy's blue-water ambitions. While a blue-water navy can project sea control power into another nation's littoral waters, it remains susceptible to threats from less capable forces (asymmetric warfare). Maintenance and logistics at range have high costs, and there might be a saturation advantage over a deployed force through the use of land-based air or surface-to-surface missile assets, diesel-electric submarines, or asymmetric tactics with fast attack craft (FAC). An example of this vulnerability was the October 2000 USS Cole bombing in Aden.
The term 'blue-water navy' should not be confused with the capability of an individual ship. For example, vessels of a green-water navy can often operate in blue water for short periods of time. A number of nations have extensive maritime assets but lack the capability to maintain the required sustainable logistic reach. Some of them join coalition task groups in blue-water deployments such as anti-piracy patrols off Somalia.
Definitions According to a dictionary definition, blue-water capability refers to an oceangoing fleet able to operate on the high seas far from its nation's home ports. Some operate throughout the world.Dictionary: Blue-water, dictionary.com
In their 2012 publication, "Sea Power and the Asia-Pacific", professors Geoffrey Till and Patrick C. Bratton outlined what they termed as "concise criteria" with regard to the definitions of brown-, green- and blue-water navies. Quote; "...a brown-water navy standing for a navy capable of defending its coastal zones, a green-water navy for a navy competent to operate in regional sea and finally [a] blue-water navy described as a navy with capability to operate across the deep waters." They go on to say that even with such a definition and understanding of naval hierarchy, it is still "ambiguous". For example, while France and the United States may be considered blue-water navies, he states that the "operational capability and geographic reach of both navies are definitely different."
Another definition states that 'brown-water' refers to the littoral areas within 100 nautical miles of the coastline. 'Green-water' begins from 100 nautical miles out to the next major land formation, while 'blue-water' is the ability to project force out to at least 1,500 nautical miles beyond the coast. Traditionally a distinction used to be made between a coastal brown-water navy operating in the littoral zone to 200 nautical miles (or 370 kilometres) and an oceangoing blue-water navy. However, the United States Navy created a new term, green-water navy, to replace the term 'brown-water navy' in US Navy parlance.U.S. Navy Chief of Naval Operations Admiral Michael Mullen pointed out in an interview with KQV (Pittsburgh): "We are looking at, in addition to the blue-water ships which I would characterize and describe as our aircraft carriers and other ships that support that kind of capability, we're also looking to develop capability in what I call the green-water and the brown-water, and the brown-water is really the rivers . . . These are challenges we all have, and we need to work together to ensure that the sea lanes are secure." FC KQV RADIO (PITTSBURGH) INTERVIEW WITH JOE FENN MAY 19, 2006 Today, a brown-water navy has come to be known as a predominantly riverine and littoral force.
Despite the above, however, there is no agreed definition of the term.
Classification and naval hierarchy
There have been many attempts by naval scholars and other authorities to classify world navies, including Michael Morris, British naval historians Eric Grove and Professor Geoffrey Till, French strategist Hervé Coutau-BégarieHervé Coutau-Bégarie, Traité de stratégie, (Economica: Paris 2002). pp 617-621, and professors Daniel Todd and Michael Lindberg. All identify basic common criteria for gauging the capability of navies, such as: total displacement and number of ships; modernity and power of weapons and systems; logistical and geographic reach with capacity for sustained operations; and the professional qualifications/disposition of sailors.
The table below shows the world naval hierarchy according to the classification system by professors Daniel Todd and Michael Lindberg. Their system originates from 1996 and outlines ten ranks, distinguished by capability. Since then it has been used by various other experts to illustrate the subject. According to Todd and Lindberg, a "blue-water navy" is one that can project any sort of power beyond its own territorial waters. However they used the principle of loss of strength gradient and other criteria to distinguish navies by capability under the four "blue-water" ranks. The six ranks of "Non blue-water navies" can be further broken down into "green-water" and "brown-water navies", and according to Todd and Lindberg, these are navies only capable of operating as coastal defence forces, coast guards or riverine forces.
+ World Naval Hierarchy, according to the Todd & Lindberg classification system (c.2015) Category Rank Designation Capabilities Navies Blue-water navies 1 power projection Multiple and sustained power projection missions globally United States 2 Limited global-reachpower projection At least one major power projection operation globally 3 Multi-regionalpower projection Power projection to regions adjacent to its own China, Italy, Japan, Russia 4 Regionalpower projection Limited range power projection beyond exclusive economic zone (EEZ) Australia, Brazil, Egypt, Germany, Netherlands, South Korea, Spain Green-water navies 5 Regional offshorecoastal defence Coastal defence within and slightly beyond EEZ Canada,Bringing the navy up to date. Legion magazine. October 4, 2019. Indonesia, Israel, Malaysia, Pakistan, Singapore, Thailand, Vietnam, and others 6 Inshorecoastal defence Coastal defence confined to inner EEZ Bangladesh, Brunei, Myanmar, North Korea, Sri Lanka, Sweden,Friedner Parrat, C., 2022. Swedish Coastal Defence Over Four Centuries: War as a Changing Institution of International Society. Scandinavian Journal of Military Studies, 5(1), p.350–363.DOI: https://doi.org/10.31374/sjms.156 and others Brown-water navies 7 Regional offshoreconstabulary Maritime policing within and slightly beyond EEZ Estonia, Iceland, Iraq, Ireland, Tunisia, and others 8 Inshoreconstabulary Maritime policing confined well within EEZ Cambodia, Cyprus, the Philippines, and others 9 Inland waterwayriverine Riverine defence of landlocked states Bolivia, Burundi, Paraguay, and many others 10 Token navyriverine Very basic constabulary if at all Many examples worldwide
Overseas basing
Historically, and to present day, blue-water navies have tended to establish overseas bases to extend the reach of supply lines, provide repair facilities and enhance the "effective striking power" of a fleet beyond the capabilities provided by the nation's homeports. Generally, these overseas bases are located within areas where potential conflicts or threats to the nation's interests may arise. For example, since World War II the Royal Navy and later the United States Navy have continued to base forces in Bahrain for operations in the Persian Gulf. The military importance and value of overseas basing is primarily dependent on geographical location. A base located at choke points in narrow or enclosed seas can be of high value, especially if positioned near, or within striking distance of an enemy's sea lines of communications. However advanced operating bases (or forward operating bases) can be equally as valuable. Naval Station Pearl Harbor acts as a "gateway" for the US Navy to "operate forward" in the Pacific Ocean.CNO Sees Hawaii as 'Gateway' to Operate Forward, navy.mil, 1/20/2012
Examples These are examples of navies that have been described by various defense experts or academics as being blue-water navies. Some have successfully used their blue-water capabilities to exercise control on the high seas and from there have projected power into other nations' littoral waters. However, there is no agreed upon definition among authorities as to what constitutes a blue-water navy.
China
The People's Liberation Army Navy (PLAN) is subject to a variety of assessments regarding its capabilities. China's ambition from a green-water navy to blue-water capabilities received much attention, particularly from the United States CongressRonald O'Rourke, "China Naval Modernization: Implications for U.S. Navy Capabilities—Background and Issues for Congress", December 10, 2012, page 7 and Department of Defense, with both acknowledging that China's primary aim was to project power in the First and Second island chains.
Since 2008, the PLAN has conducted anti-piracy missions in the Gulf of Aden on a continuous basis. In a 2013 report to Congress, defense experts also asserted that over the coming decades, China would gain the capability to project power across the globe – similar to Britain's 1982 Falklands War. In 2015, Todd and Lindberg's classification system put the PLAN was a rank four "regional power projection navy".
In 2020, assessments by the United States Naval Institute indirectly considered the Chinese Navy as a blue-water navy in all but its name, coining them "in terms of modern warships and submarines, China far outstrips any erstwhile naval competitors, except for the United States." In 2025, China conducted naval exercises in the Tasman Sea, which has been viewed by analysts as evidence of their blue-water navy capabilities.
France
The French Navy is recognised as being a blue-water navy by various experts and academics. According to professors Daniel Todd and Michael Lindberg, the French Navy is a rank two "limited global-reach power projection navy".