South Korean jets on Tuesday fired 360 rounds of warning shots after a Russian military aircraft violated its airspace, officials at the country’s Ministry of Defence said, according to BBC. Authorities said that the plane had violated the airspace over the Dokdo/Takeshima islands, which are occupied by Seoul but are also claimed by Japan. This is the first such incident involving the two countries.

Three Russian military aircraft – two Tu-95 bombers and an A-50 aircraft – had, earlier in the day, entered the South Korean airspace’s identification zone, The Guardian quoted defence officials as saying. The aircraft had initially left the area but returned to violate the airspace again later on Tuesday, following which the fighter jets were fired at by South Korea.

However, Russia’s Ministry of Defence denied that its planes had violated Seoul’s airspace, saying that its jets were carrying out planned drills over international waters. “Two Tu-95 strategic bombers of Russia’s aerospace forces carried out a planned flight in the airspace above the neutral waters of the Sea of Japan,” the foreign ministry said in a statement, according to AFP.

South Korea’s defence ministry said that the aircraft that violated its airspace was one of the three Russian and two Chinese military warplanes that had entered the Korea Air Defense Identification Zone – a space where aircraft must identify themselves before entering. Russian and Chinese bombers and reconnaissance planes have on certain instances entered the area in recent years. South Korea said that it had deployed F-15k and F-16k jets to intercept the aircraft.

“We take a very grave view of this situation and, if it is repeated, we will take even stronger action,” the South Korean president’s office quoted the head of National Security Office Chung Eui-yong as saying, BBC reported.

China has not commented on South Korea’s claims that two Chinese aircraft had entered Seoul’s air defence zone of the southwest coast earlier on Tuesday.