A strong ASW is required to counter the N Korean threat. While there has been significant joint surface warfare training between US and south Korea land, air and surface navy forces the same is not true with regards to submarine operation primarily due to US excessive secrecy on submarine operations and ASW. Although south Korea has operated submarines for more than 20 years it could learn a lot from US counterparts and advocates that Washington increases the sharing of information on tactical operations. U S responds that there is justification of limited sharing only due to cases of unauthorized disclosure of classified information of or attempts at reverse engineering

In July 2016, the United States and South Korea agreed to deploy a U.S. Terminal High Altitude Area Defense (THAAD) system and corresponding AN/TPY-2 radar in South Korea in response to North Korea’s provocative actions. The three tier system comprises of the three ship based SM-2 Aegis System (long range missile defence systems) and ESSM (Medium-range air defense system) based on the three ‘Sejong the Great’ class destroyers as the outer most layer followed by the THAAD system and the inner layer comprising of MIM-104 Patriot/PAC-2 medium to long range air defense (PAC-2 GEM/ T Interceptors), Chunma (K-SAM) short range air defence system, Chiron Missile System and Mistral Missile System and KM-SAM medium range air defence systems.
RoKN is the key agency which is rapidly modernizing to be prepared for the underwater threat. The service is undergoing a transformation into a blue-water force with quantum enhancement and modernisation of its anti-submarine warfare (ASW) capabilities. The Navy’s impetus stems from a 2010 experience in which ROK forces detected only 28% of North Korean submarines involved in exercises . Currently, while the RoKN would be somewhat able to maintain a barrier to prevent a sub from crossing over, it and its allies would not be able to keep a continuous surveillance of all North Korean submarines to detect, track and intercept any sub launched long range missiles from within its waters prior to launch, making the North Korean Submarine threat very real.