It was found that Seoul's Defense Ministry briefed Japan on measures it would take if and when Japanese patrol aircraft carry out low-altitude flights near South Korean warships.

According to Japanese media reports, Seoul said it would direct its fire-control radar at a Japanese military plane should it come as close as three nautical miles --- roughly five-point-five kilometers --- to a South Korean naval vessel.

The Defense Ministry denied disclosing its response manual and detailed operational procedures to Japan, but explained that it cannot confirm further details of the matter due to operational security.

But a ministry official said that Seoul did explain its military response measures related to a Japanese aircraft's low-altitude flyby when the ministry called in a military attache from the Japanese embassy in Seoul in January.

The ministry at the time is known to have emphasized that such behavior is a clear breach of international practices and a very dangerous act that can cause accidental clashes at sea.

Seoul made it clear then that it will sternly respond in line with its code of conduct if such behavior occurs in the future.

A ministry official also noted that Japan requested Seoul withdraw the response measures during recent working-level talks.