The ongoing radar spat between South Korea and Japan is deepening, with the two sides clashing over the matter of sharing the frequency of the radar signal that Tokyo claims to have detected. Japan insists that a South Korean Navy destroyer locked its weapons-targeting radar onto a Japanese warplane during a recent search and rescue operation, but South Korea denies the allegation.

The Ministry of National Defense said Wednesday that it had asked Tokyo to reveal the frequency of the radar that it claims to have detected so that the two sides can examine the data together. Japan refused and asked for the complete frequency information for the Navy destroyer’s fire-control radar, the ministry said. 

The two sides held the first meeting for military generals to discuss the issue in Singapore on Monday.

The incident occurred Dec. 20, when the South Korean Navy’s Gwanggaeto the Great destroyer was conducting an operation to assist a North Korean fishing boat that was drifting on international waters in the East Sea. Tokyo says the South Korean destroyer’s fire-control radar (STIR-180) locked onto a Japanese maritime patrol plane that was flying overhead for surveillance purposes.

“We asked Japan to reveal the frequency of the radar signal that it claims to have detected. But in return Japan is asking for the complete frequency information for the fire-control radar signal,” an official from the Defense Ministry said on condition of anonymity.

“No country will reveal the complete frequency information for a fire-control radar signal as it is classified as confidential military information. Japan’s demand (for the information) is disrespectful.”

Japan also refused to answer whether its warplane’s radar warning receiver system had gone off when it detected radar signals from the South Korean destroyer, citing military security. A radar warning receiver is a device that detects radar signals and converts electromagnetic waves to radio waves.

However, Tokyo claims that it sought to present Seoul with the data that had been requested and that Seoul was refusing to accept it.

According to a report published Tuesday in the Japanese newspaper the Asahi Shimbun, Japanese Defense Minister Takeshi Iwaya said Japan had suggested presenting “voice and radio-wave data” collected by the patrol aircraft showing that the destroyer had locked its fire-control radar on the Japanese warplane. The minister was quoted in the report as saying Seoul had declined to accept the data.

Denouncing Japan’s request for the confidential information as unfair, South Korea’s Defense Ministry said it was sure its Navy destroyer had not sent out any signals.

“We have clear-cut scientific evidence to corroborate our position that our STIR did not send out any signal,” a Defense Ministry official said.

Seoul maintains that the warship was on a mission to rescue a North Korean vessel drifting in the overlapping exclusive economic zones of South Korea and Japan and that it had used only the search radar, not the tracking radar.

The Defense Ministry also demanded an apology from Japan, saying the patrol aircraft had flown too close to Korea’s destroyer and that Japan had breached international customs.

By Jo He-rim (herim@heraldcorp.com)