Russian officials have called for an investigation over claims that one of its military planes violated South Korean airspace.
The US also called for close consultation between Washington and Seoul to deal with similar incidents in the future.
Seoul said South Korean fighter jets fired 360 rounds of warning shots to drive away the Russian reconnaissance plane that entered its airspace twice Tuesday during a joint patrol with Chinese bombers.
Russia and China said none of their planes entered South Korean territory.
South Korea’s defence ministry said it would hold talks with officials from the Russian Embassy on Thursday and that it has evidence that can prove Russia’s territorial trespassing.
South Korea says the incident marked the first airspace violation by a foreign military plane since the end of the 1950-53 Korean War.
Seoul officials said five Russian and Chinese warplanes, including that Russian reconnaissance aircraft, made a highly unusual joint entrance to South Korea’s air defence identification zone, prompting South Korean fighter jets to scramble.
Such a zone is not a country’s territorial sky and extends beyond it.
It is meant to give authorities an early warning of a possible incursion.
Some experts in South Korea say Russia and China may have wanted to see how decades-long trilateral security co-operation among South Korea, Japan and the United States would work amid escalating trade disputes between Seoul and Tokyo.
They say China, embroiled in a separate trade war with the US, may have also attempted to display its military co-operation with Russia.
China’s defence ministry said Wednesday that China and Russia carried out their first joint air patrol in north-east Asia that “does not target any third party”.
Spokesman Wu Qian said in Beijing that the two countries each sent two bombers for the patrols along established air routes and that they “didn’t enter the territorial airspace of other countries”.
In a message to South Korea on Wednesday, Russia repeated its position that none of its planes violated South Korean territory and that South Korean fighter jets threatened its planes with “unprofessional manoeuvres,” according to Seoul’s defence ministry.
Earlier Wednesday, Russia’s acting ambassador to South Korea, Maxim Volkov, told Yoon Sang-hyun, chairman of the South Korean parliament’s foreign affairs committee, that Russia felt the incident was “regrettable”, according to Mr Yoon.
Mr Yoon cited Mr Volkov as saying Russia thought an investigation was necessary and had requested related South Korean information.
Mr Volkov told reporters he had explained to Mr Yoon Russia’s position on the incident, but declined to provide the contents of their conversation.
Also Wednesday, South Korea’s presidential national security director, Chung Eui-yong, discussed the issue with visiting US national security adviser John Bolton.
Mr Chung told Mr Bolton about South Korea’s “resolute” response to the Russian airspace violation, and Mr Bolton proposed that the allies closely co-ordinate over similar future incidents, South Korea’s presidential office said in a statement.
Russia says two of its bombers were on a routine flight over neutral waters.
Russia’s defence ministry also denied on Tuesday that South Korean jets fired warning shots.
The South Korean foreign and defence ministries on Tuesday summoned Mr Volkov and Russia’s deputy military attache in South Korea, Nikolai Marchenko, to register their complaints.
They also summoned China’s ambassador and the defence attache to protest against Beijing’s overflight.
The airspace that South Korea says the Russian reconnaissance plane entered is above a group of islets controlled by South Korea but also claimed by Japan.
Japan subsequently protested against both Russian and South Korean actions, according to chief cabinet secretary Yoshihide Suga.