The General Security of Military Information Agreement, better known as GSOMIA, is the only military agreement made between South Korea and Japan since Korea's liberation from Imperial Japan in 1945.
The agreement was signed on November 2016 after negotiations began in 2011.
The then-defense ministers of both countries, Kim Kwan-jin and Kitazawa Toshimi, brought up the need for the agreement.
Under GSOMIA, South Korea and Japan must share all classified military information on North Korea's nuclear development and missiles that has grade 2 classification or below.
The main purpose of the agreement is to provide information the other side lacks as South Korean radar cannot observe the moment a North Korean missile drops into the East Sea while Japan lacks information about the moment a missile gets launched.
Any information exchanged between the two countries must stay within the two countries.
This year, Seoul and Tokyo exchanged classified military information about North Korea 7 times, starting from May 9th when Pyeongyang launched a short-range ballistic missile KN-23, and most recently on last Friday when Pyeongyang launched a new tactical weapon with similar traits to the U.S. Army's tactical missile system, known as ATACMS.
Hong Yoo, Arirang News.