September 15, 2012: South Korea recently put another "Sejong The Great" class destroyer into service after nine months of sea trials. This is the third, and possibly last, of these Aegis equipped warships. The first one entered service four years ago. These ships are also called KDX-III (Korean Destroyer Experimental) class guided missile destroyers and were designed to operate far from South Korea. This was part of a plan to give South Korea an international (or at least regional) naval capability. That plan changed two years ago after North Korea sank a South Korean corvette with a torpedo and shelled a South Korean island off the west coast. Now South Korea is scrambling to build more coast protection vessels and enhance anti-submarine capabilities.

The KDX III was preceded by the 3,900 ton KDX-I in 1998, and the 5,500 ton KDX-II in 2002. The 9,900 ton KDX-IIIs are approximately the same size as the U.S. Navy's Arleigh Burke class guided missile destroyers. Actually, the KDX III is a little larger than the Burkes and have 128 VLS cells for missiles, compared to 96 on the Burkes. The VLS tubes usually carry 80 SM-2 anti-aircraft missiles, 32 cruise missiles, and 16 rocket launched anti-submarine torpedoes. There are also six anti-submarine torpedo tubes. There is also a 6 inch (127mm) gun, two 30mm auto-cannon, and a multiple cell launcher of Rolling Airframe Missiles for anti-missile defense. The KDX can also carry two helicopters. The KDX-III is the first Korean ship large enough to carry the AEGIS system and may get an anti-missile upgrade (which some Japanese Aegis ships have). Built in South Korea the KDX IIIs cost about $930 million each.

Instead of building more KDX IIIs, there is more interest in having more KDX IIs and modernizing the ones already in service. Six KDX IIs are already in service and they are adequate for dealing with North Korea and China. Meanwhile, the third KDX III had an additional hundred tons of torpedo protection added to its hull. South Korea is also seriously considering upgrading the Aegis air defense systems on the KDX III so that it can use the anti-missile version of the SM-2 anti-aircraft missile or the even more capable SM-3 anti-missile missile. South Korea says that its KDX-III Aegis radar can currently spot any ballistic missile launch in North Korea.