Seoul(CNN) Warplanes from four countries faced off Tuesday in a chaotic and unprecedented confrontation above a small, disputed island off the coast of South Korea and Japan.
South Korea's Joint Chiefs of Staff issued a statement claiming they had fired more than 300 warning shots at a Russian A-50 command and control military aircraft early Tuesday morning after it had twice violated the country's airspace, the first such incident between the countries.
Moscow furiously denied Seoul's account of the encounter, claiming that South Korean military jets had dangerously intercepted two of its bombers during a planned flight over neutral waters.
But in a statement Tuesday afternoon, Japan's Ministry of Defense backed up South Korea's claims, saying the A-50 had flown over the islands and that Tokyo had scrambled fighters to intercept.
In a further complication, both South Korea and Japan said that two Chinese H-6 bombers had joined the Russian military aircraft on sorties through the region as well.
The confrontation took place over disputed islands in the East Sea, also known as the Sea of Japan, in the early hours of Tuesday morning.
What triggered the confrontation or why the planes were in the region is unclear, but analysts said the mission may have been designed by Russia to draw out South Korean and Japanese aircraft for intelligence gathering purposes.
"This mission will have given them a comprehensive map of the (South Korean) national air defense system," said Peter Layton, a former Royal Australian Air Force pilot and analyst at the Griffith Asia Institute.
The incident came during what South Korean officials have claimed was a joint Russian-Chinese military exercise.
According to South Korea, two Chinese H-6 bombers passed into Seoul's Air Defense Identification Zone (KADIZ) beginning from 6.44 a.m., joined by two Russian Tu-95 strategic bombers.
The four planes then entered the KADIZ together at about 8.40 a.m. and remained there for 24 minutes.
Airspace is defined as the area 12 nautical miles from a country's borders, which falls entirely under its control. An ADIZ is an area in which the controlling country demands identification, location and control of aircraft's direction, but doesn't necessarily have any rights of engagement under international law.
South Korea's KADIZ was first established in 1950 and most recently adjusted by Seoul in 2013.
After the KADIZ flyover, Seoul said a Russian A-50 flew above the contested islands first at 9.09 a.m. local time and then again at 9.33 a.m., each time for just a matter of minutes.
In response, South Korea deployed F-15F and KF-16 fighter jets, the statement said, and fired 360 warning shots ahead of the Russian aircraft, 80 during the first violation and 280 during the second. The shots were fired using 20mm weapons, according to the country's Ministry of Defense.
The South Korean military said they also sent out 30 warnings to the Russian plane but received no response. The A-50 is an unarmed AWACS plane, standing for Airborne Warning and Control System, designed for tracking and observation.
In a statement on Tuesday afternoon, the Russian Defense Ministry confirmed its aircraft had taken part in a "joint patrol" with Chinese long-range aircraft and said that they were conducting the "first joint air patrol using long range aircraft in the Asian-Pacific region."
The statement said that two Russian Tu-95 bombers and two Chinese H-6 bombers had conducted an air patrol over the waters of the Japan and East China Seas.
It added that the patrol was "carried out in order to deepen and develop Russian-Chinese relations" and was "not aimed against third countries."
Earlier in the day, the Defense Ministry furiously denied the South Korean reports and accused South Korean fighter pilots of acting inappropriately.
"(They) conduced unprofessional maneuvers by crossing the course of Russian strategic missile carriers, threatening their security," the ministry said in the statement.
"This is not the first time the South Korean pilots have unsuccessfully tried to prevent Russian aircraft from flying over the neutral waters," the Russian statement said, adding it didn't recognize South Korea's KADIZ.
Although neither of those statements made any reference to the A-50, later on Tuesday, in an on-camera statement, the commander of the Russian Air Forces Long Range Aviation Lieutenant-General Sergey Kobylash said that the mission was "supported" by the A-50 and KJ-2000.
He also denied that there was any "warning fire," from the South Korea fighters and said: "If Russian pilots had identified such a threat, an immediate adequate response would have followed."
After Moscow released its initial statement, Japan confirmed it had also scrambled fighter jets in response to the Russian incursion Tuesday.
"We confirmed Russia's A-50 has invaded Japan's airspace while two of Russian TU-95 bombers and two Chinese H-6 bombers flew around Japan. We took measures against the invasion," said a spokesman for the country's Ministry of Defense.
When asked about the incident, the Chinese Ministry of Foreign Affairs said they weren't aware of the details and referred the question to the Defense Department.
"You used the word 'intrusion' and I'd caution against using such terms, considering China and South Korea are friendly neighbors and the situation is not clear yet," spokeswoman Hua Chunying said.
Chung Eui-yong, director of South Korea's National Security Office, said that he had sent a "strong" message of complaint to the Russian authorities over the incident.
"We are taking this situation very seriously, and if this kind of action is repeated, we will take even stronger measures," Chung said, without detailing what those measures could be.
The Japanese government said that it had issued a strong protest against both the Russian and the South Korean governments for intruding on what they regard as their airspace.
The South Koreans said they had dismissed Japan's protests. Moscow has not responded to either country's concerns.
Carl Schuster, a former director of operations at the United States' Pacific Command's Joint Intelligence Center, said that shooting a warning shot in the air was "very very serious" and "very, very rare."
Schuster said that the fact shots were fired meant Seoul had viewed the violation as a serious and deliberate act, adding he couldn't explain why the Russian plane would come back again after the first warning.
"Penetrating to a point of requiring warning shots to turn away is normally the result of a deliberate decision to penetrate that airspace," he said.
On Tuesday, Pentagon Spokesman Lt. Col. Dave Eastburn told CNN that the United States' is in "close coordination" with their Korean and Japanese allies and that the US "will continue to monitor activities as they follow up with their Russian and Chinese counterparts through diplomatic channels."
"The United States' commitment to the defense of its allies is ironclad," he added.
Though East Asia is riven by numerous, long-standing territorial disputes, Russia and South Korea rarely come into conflict.
Top Russian and South Korean leaders at the G20 in Osaka, Japan, in June, where they praised their warming bilateral relations. Russian President Vladimir Putin said South Korea was "one of our key partners" in Asia.
It is the second tense incident involving the Russian military in East Asia in less than two months. On June 8 two vessels from the United States and Russia almost collided in the Pacific, coming within 50 feet of each other.
The exact location of the standoff wasn't clear but it was believed to take place in the waters off the coast of China.
Relations between Beijing and Moscow have reached an "unprecedented" peak in the past year, according to Russia's Putin, including growing cooperation between their two militaries.