Green-water navy

Green-water navy is terminology created to describe a naval force that is designed to operate in its nation's littoral zones and has the competency to operate in the open oceans of its surrounding region. It is a relatively new term, and has been created to better distinguish, and add nuance, between two long-standing descriptors: blue-water navy and brown-water navy.

It is a non-doctrinal naval term used in different ways. It originates with the United States Navy, who use it to refer to the portion of their fleet that specializes in offensive operations in coastal waters. Nowadays such ships rely on stealth or speed to avoid destruction by shore batteries or land-based aircraft.

The US Navy has also used the term to refer to the first phase of the expansion of China's navy into a full blue-water navy. Subsequently other authors have applied it to other national navies that can project power locally, but cannot sustain operations at range without the help of other countries. Such navies typically have amphibious ships and sometimes small aircraft carriers, which can be escorted by destroyers and frigates with some logistical support from tankers and other auxiliaries.

The elements of maritime geography are loosely defined and their meanings have changed throughout history. The US's 2010 Naval Operations Concept defines blue water as "the open ocean", green water as "coastal waters, ports and harbors", and brown water as "navigable rivers and their estuaries". Robert Rubel of the US Naval War College includes bays in his definition of brown water, and in the past US military commentators have extended brown water out to 100 nautical miles (190 km) from shore.

During the Cold War, green water denoted those areas of ocean in which naval forces might encounter land-based aircraft. The development of long-range bombers with anti-ship missiles turned most of the oceans to "green" and the term all but disappeared. After the Cold War, US amphibious task forces were sometimes referred to as the green-water navy, in contrast to the blue-water carrier battle groups. This distinction disappeared as increasing threats in coastal waters forced the amphibious ships further offshore, delivering assaults by helicopter and tiltrotor from over the horizon. This prompted the development of ships designed to operate in such waters – the Zumwalt-class destroyer and the littoral combat ships; modelling has suggested that current NATO frigates are vulnerable to swarms of 4-8 small boats in green water. Rubel has proposed redefining green water as those areas of ocean which are too dangerous for high-value units, requiring offensive power to be dispersed into smaller vessels such as submarines that can use stealth and other characteristics to survive. Under his scheme, brown water would be zones in which ocean-going units could not operate at all, including rivers, minefields, straits and other choke points.

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