South Korea has developed an anti-ship missile based on the U.S. Harpoon. The Haeseong missile will equip South Koreas new KDX missile destroyers. The Harpoon is a 30 year old design, that has undergone several upgrades over the years. The South Koreans have not released a lot of details on their missile, except that it has a range of 150 kilometers, and is intended as a Harpoon replacement. The latest version of Harpoon has a range of 140 kilometers and GPS guidance to get the missile to the general area of the target, and an elaborate terminal guidance system to put the missile into an enemy ship (without being distracted by countermeasures.) The South Koreans spent over a hundred million dollars developing the Haeseong, so it appears that they did not just clone the original, 1970s, Harpoon design (which used radar for terminal guidance), but improved on it. South Korea likes to keep the capabilities of its weapons secret, because it faces a real threat from the heavily armed North Korean armed forces. So Haeseong probably has the latest electronic bells and whistles.