South Korea is buying 84 of the Standard 2 (SM-2 Block IV) anti-missile missiles. This version is effective against ballistic missile warheads that are about to hit their target. In one test, a SM-2 Block IV missile destroyed a warhead that was only 19 kilometers up. The more specialized (and, at $3 million, twice as expensive) SM-3 missile can destroy a warhead that is more than 200 kilometers up. But the SM-3 is only good for anti-missile work, while the SM-2 Block IV can be used against both ballistic missiles and aircraft. South Korea has already purchased the anti-aircraft version (Block IIIB) of the SM-2 for their KDX III class Aegis destroyers.
Last December, South Korea put into service the its first (of three) Aegis equipped destroyers; "Sejong The Great." This is a KDX-III (Korean Destroyer Experimental) class guided missile ship. It 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 destroyer. 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 KDX can also carry two helicopters.
The KDX-III is the first Korean ship large enough to carry the AEGIS system, and is now getting the anti-missile upgrade (which some Japanese Aegis ships have). Built in South Korea, the KDX IIIs cost about $900 million each. All three KDX IIIs should be in service by 2012.