South Korea is establishing two high seas ("blue water") squadrons, each with a 7,600 ton KDX III Aegis destroyer, and three 4,500 ton destroyers, plus maritime patrol aircraft and support ships. This is a major shift for South Korea, which has long concentrated its naval power on coastal defense, against North Korean attack. But the North Korean navy, and armed forces in general, have been declining for over a decade, because the country has been going broke from mismanagement and the disappearance of Cold War era subsidies from the Soviet Union.
Part of this high seas strategy is the building of a new naval base on the island of Jeju, off the south coast, in the straights between Korea and Japan. Construction will be completed in five years. Three KDX III Aegis destroyers are being built. One is in service, and the second will be commissioned later this year. Each of these ships carries two helicopters, in addition to anti-ship and anti-aircraft missiles. South Korea is also building a class of 1,800 ton submarines, for high seas operations.