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South Korea, Diplomatic Strain and the Radar Lock-on Incident 

The outcome of Japan-South Korea talks in Singapore led one Japanese lawmaker to laud both sides, saying "resuming exchanges serves national interests."



Defense Minister Minoru Kihara meets with his South Korean counterpart, Shin Wonsik, in Singapore on the sidelines of the 2024 Shangri-La Dialogue. (courtesy of the Ministry of Defense, Kyodo News)

In Singapore on June 1, Japan and South Korea convened for a defense ministerial meeting. Both nations agreed to prevent future military-related incidents from hampering bilateral relations. A notable past incident was the South Korean Navy's radar lock-on of a Maritime Self-Defense Force (MSDF) aircraft. Setting aside the bitterness of that incident, the June 1 agreement aims to facilitate the resumption of defense exchanges.

However, shelving the clarification of facts has left strong discontent among conservative factions in Japan, including the Liberal Democratic Party. Japan has substantial evidence backing its claims, which makes South Korea's outright denial seem unfounded and implausible. However, recently, it has come to light that South Korean military personnel unofficially explained the entire sequence of events to Japan. Their testimonies included the suppression of the truth behind the incident, reportedly done "at the direction of then-President Moon Jae In."

Context and Controversy

The radar lock-on incident occurred on December 20, 2018, around 3:00 PM, off the Noto Peninsula within Japan's exclusive economic zone. In this area, also known as the Yamatotai fishing grounds, a MSDF P-1 patrol aircraft was conducting routine surveillance. 

Without warning, a 3,200-ton South Korean destroyer suddenly targeted it with fire-control radar. Although the P-1 attempted to radio the destroyer to inquire about their intentions, it received no response. South Korean coast guard vessels and small boats that appeared to be fishing vessels were near the destroyer.

Japan's maritime patrol aircraft, Kawasaki P-1, is shown flying near the scene of South Korean naval and coast guard vessels rescuing a North Korean boat. The P-1 was subsequently locked on by hostile fire-control radar. (©YTN News/video taken by the Korean Coast Guard)

Tokyo immediately lodged a strong protest with Seoul. South Korea explained via diplomatic channels that they had been searching for a missing North Korean fishing vessel. According to the South Korean Ministry of National Defense (MND), "radar was used during the operation, but was not employed to track a patrol aircraft." Furthermore, South Korean media reports also stated that the Republic of Korea Navy acknowledged it had used fire control radar.

However, five days after the incident, the MND completely reversed course. It denied any radar lock-on, stating, "Cameras were used, but no lock-on occurred." 

From that point onward, Seoul maintained its denial, demanding an apology from Japan and condemning the Japanese patrol aircraft's low-altitude flight as dangerous. On January 21, 2019, the Japanese government issued an unprecedented "final statement." It thereupon terminated discussions with South Korea.

As If It Never Happened

A former Japanese Ministry of Defense (MOD) official stated, "It seems the South Korean MND planned to disclose the truth to Japan." About a week after the incident, a contact from within the MND informed their Japanese counterparts of the timeline of events. 

According to their conversation, events unfolded as follows.

South Korean Defense Minister (at the time) Jeong Kyeong-doo reportedly briefed the Blue House (Presidential Office) on the incident. President Moon Jae In then ordered him to "act as if it never happened." Consequently, the MND was effectively silenced on the matter. Nevertheless, Jeong asked some retired South Korean military officials to convey the full details to officials in Japan's MOD.

As per their explanation, Pyongyang requested the Blue House to detain individuals who had fled on a fishing boat. A destroyer engaged in exercises in the vicinity rushed to the scene. When the P1 spotted the destroyer, it was in the process of retrieving the body of a North Korean who had jumped into the sea. The South Korean military secured three North Korean defectors and one body. Two days later, the Ministry of Unification announced that they had been repatriated to North Korea. However, no footage or photos of the repatriation were released.

Something to Hide?

A retired MOD official testified, "I heard that the military sent them back to North Korea four or five hours after transporting them to the port." Why were they in such a rush?

If this account is accurate, it suggests that the South Korean destroyer was highly wary of being captured on film by the P1 during the operation. This would explain why it resorted to the drastic measure of radar lock-on. Moreover, the Moon administration likely feared Japanese scrutiny exposing its complicity with North Korea on the request.

"There seemed to be a willingness among the MND to acknowledge the truth and apologize," the retired Japanese defense official stated. "However, they were under strict presidential orders prohibiting any disclosure. It's possible they may have intended to relay this to the Japanese government." While reportedly brought to the attention of the Shinzo Abe administration, it seems government officials handled it as unofficial information.

Political Considerations and Strategic Impact

Former Defense Minister Gen Nakatani is well-versed in the details of the radar lock-on case. He has consistently pointed out that the MND initially admitted to the radar lock-on but later asserted it "never occurred."

"I saw this as an incident where political considerations influenced military actions," Nakatani reflects. Speaking about the recent decision to defer resolving the matter, he stated, "The radar incident became a thorn in the side amid improving relations between leaders. I think it was a pragmatic decision that resuming exchanges serves national interests."

Defense Minister Minoru Kihara (leftmost) and South Korean Defense Minister Shin Wonsik(rightmost) pose for a commemorative photo flanked by their senior naval officers before their meeting. June 1, Singapore (courtesy of the Ministry of Defense).

At the time, Vice Admiral Yoji Koda, former commander of the MSDF, meticulously analyzed the video footage. "It was odd for both destroyers and maritime police to approach a vessel in distress," he remarked. "Based on my extensive experience in maritime rescues, I can confidently say that it bore no resemblance to a typical rescue operation. They didn't even attempt to toss out a rope." Koda's analysis debunked South Korea's false claims.

He also addressed the resumption of defense exchanges between Japan and South Korea. "We must consider potential contingencies on the Korean Peninsula or the Taiwan Strait. Unless Tokyo and Seoul become key strategic partners, we'll be the laughingstock of our enemies."

The North Korean Connection

Is it possible to re-investigate the facts concealed by the previous administration? Some speculate that the repatriated defectors were targets of a large-scale purge. 

Under Kim Jong Un's regime, the Korean Workers' Party leadership conducted this purge between May and December 2018. This investigation targeted senior officials of the Supreme Guard Command (SGC), Kim's personal bodyguard force. Since 2019, reports from Japan and South Korea have documented the arrest and execution of several such officials. The prevailing theory suggests that suspects were charged with an alleged plot to assassinate Kim Jong Un.

Tsutomu Nishioka is a visiting professor at Reitaku University and an expert on Korean Peninsula affairs. "Sources within North Korea indicate that those found adrift around Yamatotai included three senior officials from the SGC," he says. "They had fled with the agency director, fearing the regime would purge them."

Furthermore, according to Nishioka, "Pyongyang allegedly requested central figures in the Moon administration to apprehend and extradite the four men. In response, the South Korean navy was mobilized. Reports indicate this was when the SDF aircraft approached, and the South Korean destroyer aimed its fire-control radar at it.

Debate in Japan and South Korea has centered on whether or not radar lock-on occurred. However, the crux of the matter now lies in understanding why it happened. 

Yoon Suk-yeol's administration aims to uncover any collusion between the Moon administration and North Korea linked to the radar incident. This may help clarify the facts. 


Read the article in Japanese.

Author: Ruriko Kubota