South Korea is interested in fielding the Aegis SM-3 capability, but it seems to me it would make more sense for them to field a land-based Aegis Ashore that could be installed to provide persistent missile defense in the middle of the country:
Aegis SM-3 firing
Seoul needs to deploy U.S. ship-based missile interceptors known as RIM-161 Standard Missile 3s, or SM-3s, to complete its low-altitude air and missile defense system against North Korea, according to an internal report by South Korea’s Ministry of National Defense that was exclusively acquired by the JoongAng Ilbo Monday.
Drafted in August and handed over by Bareun Party Rep. Kim Young-woo, a member on the parliamentary National Defense Committee, the report acknowledges that South Korea’s current low-altitude defense system, also known as the Korea Air and Missile Defense, or KAMD, is unable to intercept some North Korean missiles if they were to fly across the border.
A local government source who spoke on the condition of anonymity said the military wrote the report in order to start policy discussions on how Seoul could deploy the SM-3s, which are said to be able to target any North Korean missile fired from a normal angle, filling in a gap left by the country’s current defense systems, mainly comprising the Patriot and Cheongung interceptors that can target an incoming missile up to 20 kilometers (12 miles) high, and the Terminal High Altitude Area Defense (Thaad) missile shield, which covers 40 to 150 kilometers in altitude.
An SM-3 has a range of up to 400 kilometers and can travel as far as 700 kilometers away.
The ministry stressed that the defense system would especially come in handy if North Korea carries out an electromagnetic pulse (EMP) attack, as it recently threatened.
Under that scenario, the ministry said it was likely North Korea would blast its warhead-triggered EMP about 60 to 80 kilometers above ground, which can effectively be targeted by an SM-3. [Joong Ang Ilbo]
