Analysis | Japan-S. Korea rift may risk national security issues
The South Korean government’s decision to abandon the General Security of Military Information Agreement (GSOMIA) with Japan has led to concerns that weakened cooperation between the two nations will hinder their ability to fully monitor, track and analyze ballistic missile launches by North Korea.
“We estimate that the [first] ballistic missile flew about 400 kilometers and fell outside our exclusive economic zone,” Defense Minister Takeshi Iwaya told reporters Saturday.
Iwaya said Japan’s intelligence allowed the government to quickly determine ballistic missiles had been launched, adding that “[South Korea’s announcement] on the GSOMIA had had no impact.”
When North Korea launches a ballistic missile, it is quickly detected by U.S. military early warning satellite.
The United States then shares information such as the launch site and trajectory with the Self-Defense Forces.
The SDF tracks missiles using Aegis cruisers in the Sea of Japan and radar installations on the Japanese mainland to confirm missile landing areas and other factors.
For this reason, officials say that not having access to information from the South Korean military will not pose a major problem in intercepting missiles shot toward Japan.
However, missiles that fly short distances or at low altitudes cannot be detected by Japanese radar, and without access to radar data from the South Korean military, the Japanese government may not be able to determine the flight distance, altitude, or type of missile in some cases.
In contrast, the South Korean side is frequently unable to track missiles that travel long distances using its own radar.
The GSOMIA has allowed Japan and South Korea to exchange and compare information, which has made it easier to get an accurate overall picture of the North’s missile launches. Iwaya said the government “would like to offer South Korea” intelligence on Saturday’s missile launches.
According to the South Korean government, intelligence has been exchanged with Japan via the GSOMIA 29 times.
Yonhap News reported there was one case in 2016 and 19 cases in 2017 when North Korea carried out a series of ballistic missile launches.
While there were only two cases in 2018, a time when Pyongyang refrained from military provocations, there have been seven cases so far this year.
A Japanese government source said that South Korea more often receives information from Japan due to factors such as radar capabilities, how Aegis cruisers are deployed and where missiles land.
On July 27, the South Korean newspaper Chosun Ilbo reported that according to military sources, after North Korea launched two new short-range ballistic missiles on July 25, the South Korean military twice revised calculations of how far they flew, eventually concluding they traveled 600 kilometers.
The sources said this conclusion “was affected by intelligence obtained from Japan through the GSOMIA.”
“Scrapping the GSOMIA will be detrimental to both Japan and South Korea, and will only benefit North Korea and China,” a senior Japanese Defense Ministry official said.