In mid-August, North Korea won a significant victory over three nations trying to get North Korea to give up its nuclear weapons. This event was also seen as a win for China as well. All this had was big news in East Asia but made hardly a ripple in Western news outlets. The event in question was South Korea pulling out of the 2016 GSOMIA (General Security Of Military Information Agreement) it had with Japan and the United States. The GSOMIA enabled all three nations to quickly share highly classified information each had on North Korean military activities. Given that the information often involved North Korean use of ballistic missiles and developments in their missile and nuclear weapons program, GSOMIA made it easier for the three allies to quickly analyze, interpret and act on the unique information each gathers in North Korea military developments.
For example, the South Koreans have the best HUMINT (human intelligence) as they have agents in northeastern China as well as a constant flow of North Koreans fleeing to sanctuary in South Korea and bringing personal views on what is going on there. Several times a year South Korea receives higher-level North Korea refugees, who possess even more valuable information. South Korea also has a border with North Korea (the DMZ) and uses ground and airborne intel collecting gear to monitor what North Korea are up to. Japan has a growing array of powerful radars and other sensors monitoring North Korean long-range missiles tests, which are largely conducted from the east coast of North Korea and aimed towards, and sometimes over, Japan. The U.S. has an extensive array of specialized intelligence satellites that monitor North Korea. Japan has some similar satellites, but nothing as powerful as the American capabilities.
Until the GSOMIA was agreed to in 2016, the U.S. had to use a more time consuming method of taking data on North Korea from all three nations and then getting South Korea and Japan to both take the Americans word for interpretations of data from all three nations. Also, the U.S. was required to not pass on South Korean or Japanese intel to another country (like South Korea or Japan) without permission. It took years of persistent and careful diplomacy to get South Korea and Japan to agree to join a three nation GSOMIA.
Now it was all gone and South Korea was accusing the Americans of siding with Japan. This is not the case but that’s how South Korean politics works when it comes to Japan and anyone who is an ally of Japan. What this is all about is Koreans' (north and south) anger at the bad treatment they received from Japan during World War II and the four decades that Japan ruled Korea. In the case of the GSOMIA the problem began in 2018 when the South Korean Supreme Court agreed with a South Korean lawsuit that Japan must pay more compensation for forced labor South Koreans were compelled to perform for Japan during World War II. Japan insists that earlier agreements have taken care of this but Japanese guilt is a perpetual grievance in South Korean politics and it keeps coming up again and again.
These disputes tend to escalate and that’s what happened big time and destroyed the GSOMIA. That was because Japan rejected the South Korean court decision and retaliated by halting exports of essential components for South Korean microchip manufacturers. That led to South Korea backing a boycott of Japanese goods in South Korea and when that did not persuade Japan to resume essential exports to South Korea, the next step was cancelling GSOMIA and it isn’t over yet. Meanwhile the North Korea and China see it as a significant win because it shows how easily the U.S., South Korea and Japan alliance can come apart.
Japanese atrocities during World War II are also still an issue in China and throughout East Asia but South Korea is a special case as it is a democracy with a free press and politicians and editors always have, and often use, the option to revive one of the many Japanese “crimes against humanity” and the Korean people. It is considered improper behavior for a Korean to criticize these attacks on past Japanese behavior.
This has always been a big deal in South Korea, where hatred of Japan has been a major national passion for over a century. Although South Korea and Japan have many reasons to be allies, they have a difficult time making formal agreements to cooperate against North Koreas or Chinese aggression. When pressed on this South Korea points out that because of the widespread antipathy towards Japan for past events the Japanese must do something dramatic to improve their popularity in South Korea. Japan does make friendly gestures, many of them, but it is never enough.
South Korean anger towards Japan can be traced back to the Japanese occupation, where Korea was a brutally treated Japanese possession from 1910 to 1945. The four decades of Japanese occupation were extremely cruel. Think how bad the Nazi occupation of conquered countries was during World War II and realize that the Japanese occupation of Korea was much worse and for much longer. The Japanese don’t help with their post-World War II attitude that Japan was a victim because it was forced into World War II by evil Westerners and was only trying to help its neighbors by occupying them and treating them badly. Japanese have a hard time understanding how their victims don’t appreciate all that Japan tried to do for them. What the neighbors do remember is what the Japanese did to them, something the Japanese tend to downplay or deny outright.
It’s popular in Japan to believe that, after they quickly defeated Russia in 1905 they should have been accorded more respect by the West. The Japanese seemed to overlook the fact that most European countries had defeated Russia at one time or another. Even Sweden had done so, and later on even tiny Finland would as well. The problem here was that everyone but Japan saw Japan as a major bad guy during World War II.
As a result of the 1904-5 Russo-Japanese War Japan got control over Korea in 1910, along with some German colonies, a decade later for joining the allies during World War I. Japan expected more for its World War I support and these resentments led to increased aggression against China and, eventually, to attacking the United States and European possessions in East Asia in 1941. The United States liberated what is now South Korea in 1945 while the Russians did the same in North Korea. That liberation of Korea left some other contentious loose ends.
One of these loose ends was ownership of some small islands between South Korea and Japan. Officially, South Korea suggests that Japan cede to South Korea claims on Dokdo Island in order to improve relations. South Korea has long been willing to sacrifice good relations with Japan over the issue of who owns the uninhabited Dokdo (Takeshima to the Japanese) islands in the Sea of Japan (East Sea in Korean). For a long time there was a major obstacle to obtaining agreement on the GSOMIA. But the mass media in both countries have been jumping all over the island ownership dispute. Japanese politicians believed they would take an enormous domestic political hit if they managed to get the votes to give South Korea Dokdo. But it would make Japan popular enough in South Korea to get the long-desired (by defense officials in both countries) cooperation treaty. GSOMIA was obtained without resolving the Dokdo issue and that was encouraging.
One reason for getting everyone to agree to GSOMIA was earlier good deeds. For example in 2014 both South Korea and Japan had peacekeepers in South Sudan when a civil war broke out. When that happened the South Koreans found they didn’t have enough ammo for any sustained action, something they might now have to deal with given the number of locals shooting at each other and the civilians and foreign aid workers the South Korean troops would have to defend. So on December 22nd 2014 they asked the nearby Japanese contingent if they could spare any ammo and the Japanese promptly sent 10,000 rounds. It turned out that the additional ammo was not needed and on January 10th 2015 it was returned to the Japanese. This was hailed as a good thing in Japan and South Korea but many similar incidents were not enough to eliminate early 20th century Japanese atrocities as a perennial, and dangerous, hot topic in South Korea. This is seen as a major obstacle to any cooperation against common threats, like North Korean or Chinese aggression and the GSOMIA cancellation was just the latest reminder.