The Royal Navy is the 2nd largest navy in NATO.
Coordinates: 50.8761556°N 4.4220111°E / 50°52′34.16″N 4°25′19.24″E
The North Atlantic Treaty Organization (NATO; // NAY-toh; French: Organisation du traité de l'Atlantique Nord (OTAN)), also called the (North) Atlantic Alliance, is an intergovernmental military alliance based on the North Atlantic Treaty which was signed on 4 April 1949. The organization constitutes a system of collective defence whereby its member states agree to mutual defense in response to an attack by any external party. NATO's headquarters are in Brussels, Belgium, one of the 28 member states across North America and Europe, the newest of which, Albania and Croatia, joined in April 2009. An additional 22 countries participate in NATO's "Partnership for Peace", with 15 other countries involved in institutionalized dialogue programs. The combined military spending of all NATO members constitutes over 70% of the world's defence spending.
The Royal Navy (RN) is the principal naval warfare service branch of the British Armed Forces. Tracing its origins to the 16th century, it is the oldest service branch and is known as the Senior Service. From the end of the 17th century until well into the 20th century it was the most powerful navy in the world, playing a key part in establishing the British Empire as the dominant world power. Due to this historical prominence, it is common – even among non-Britons – to refer to it as "The Royal Navy" without qualification.
Following victory in the First World War the Royal Navy was significantly reduced in size, although at the onset of the Second World War it was still the largest in the world. By the end of the Second World War the United States Navy had emerged as the world's largest. During the course of the Cold War, the Royal Navy transformed into a primarily anti-submarine force, hunting for Soviet submarines, mostly active in the GIUK gap. Following the collapse of the Soviet Union its focus has returned to global expeditionary operations around the world.