SEOUL, South Korea — South Korea said its air force jets fired hundreds of warning shots on Tuesday to ward off a Russian military plane that intruded upon its territorial airspace, the first such encounter between the countries in decades.
The Russian and Chinese aerial incursions into sensitive airspace between South Korea and Japan — two key American allies — was a daring challenge to Washington and Seoul.
Three Russian military planes, as well as two Chinese warplanes, on Tuesday entered South Korea’s air defense identification zone off its east coast, where foreign military aircraft must identify themselves in advance to South Korea, the South’s military said.
But one of the Russian planes, a Beriev A-50 early warning and control aircraft, flew closer to South Korea, intruding twice into its territorial airspace near Dokdo, a cluster of South Korean-held islets that are also claimed by Japan, the South Korean military said.
Both times, the Russian plane violated South Korea’s airspace for a few minutes, prompting South Korean F-15 and F-16 fighter jets operating nearby to fire 20 flares and 360 machine gun rounds as warning shots from a half mile away, the officials said. The South Korean jets took the action after the Russian plane did not answer repeated radio warnings.
The South Korean military provided no further details. But its officials said that it was highly unusual for Russian and Chinese planes to stage a joint flight mission over the sea between South Korea and Japan.
In recent years, long-range bombers and reconnaissance planes from the Russian and Chinese militaries have frequently entered South Korea’s air defense identification zone, prompting its air force to dispatch fighter jets to confront them.
But the episodes on Tuesday marked the first time in recent memory that a Russian warplane entered South Korea’s territorial airspace without approval, South Korean officials said.
Chung Eui-yong, the national security adviser for President Moon Jae-in of South Korea, sent a warning to his Russian counterpart, Nikolai Patrushev, secretary of Russia’s Security Council, Mr. Moon’s office said on Tuesday. It warned that South Korea would take “a far stronger action” if Russia tried similar maneuvers.
Seoul also planned to summon Russian and Chinese diplomats in South Korea to lodge a protest, officials said. And the Japanese government lodged a formal complaint against both the Russian maneuvers and South Korean machine gun barrage over “our territory,” the Kyodo News agency reported.
There was no immediate reaction from Moscow or Beijing.
Military planes that enter another country’s air defense identification zone must notify that country in advance, but in recent years countries in the region have often accused each other of violating that protocol. If a military plane enters the zone without proper notice, the host country may order it to leave, or dispatch military jets to confront the intruding aircraft.
In 2013, South Korea expanded its air defense identification zone for the first time in 62 years to include airspace over the East China Sea that is also claimed by China and Japan. With South Korea’s expansion, the air defense zones of all three countries now overlap over a submerged reef called Ieodo in South Korea and Suyan Rock in China.
South Korea expanded its air patrol zone two weeks after China stoked regional tensions by unilaterally expanding its own air patrol zone to include airspace over the reef. The expanded Chinese air control zone also covers a set of East China Sea islands, called Diaoyu in Chinese and Senkaku in Japanese, which are at the heart of a territorial feud between Japan and China.
The overlapping zones have raised the risk of military tensions in the region.