South Korea scrambled fighter jets after Russian warplanes entered South Korea's air space identification zone on Tuesday, the latest in a series of such violations, its military said.
A total of six Russian military aircraft repeatedly entered the Korea Air Defence Identification Zone (KADIZ) over a six-hour span starting 9:23 a.m. (0023 GMT), Seoul's Joint Chiefs of Staff (JCS) said.
The incident marked the 20th breach of KADIZ by a Russian military plane this year, the JCS said.
"Our military urgently dispatched fighter jets to track and monitor the aircraft and broadcast warning messages," the JCS said in a statement.
Calls to the Russian embassy in Seoul seeking comment went unanswered.
The wedge of sea between Japan, Russia, and the Korean peninsula had long been a flashpoint amid a string of regional airspace disputes.
In July, South Korean warplanes fired flares and hundreds of warning shots near Russian bombers that violated South Korean airspace during what Moscow said was its first long-range joint regional air patrol with China.
But there were no warning shots fired on Tuesday as the Russian aircraft did not enter South Korean territorial airspace, Seoul's military said.
An ADIZ is usually an area where countries may unilaterally demand that foreign aircraft take special steps to identify themselves, unlike a nation's airspace, which usually means the space above its territory.
The latest incident came a day before the South Korean and Russian militaries hold talks to discuss plans to open a hotline between their air forces as part of efforts to rein in unreported ADIZ entries.