South Korea has announced it is expanding its air defence zone, which will now partially overlap with a similar zone announced by China.
The two zones will now both include a rock claimed by both countries and controlled by South Korea.
China announced a new Air Defence Identification Zone (ADIZ) last month, in a move that raised regional tensions.
Both countries' zones will cover the airspace above a rock called Ieodo by South Korea and Suyan by China, which is claimed by both countries.
It will be the first time that South Korea has adjusted the zone since it was first set up by the US military in 1951 during the Korean War, South Korea's Yonhap news agency reports.
China's recently announced ADIZ also covers islands claimed and controlled by Japan.
China said aircraft flying through the zone must follow its rules, including filing flight plans.
The US, Japan and South Korea have rejected China's zone and flown undeclared military aircraft through the ADIZ.
"We will coordinate with related countries to fend off accidental military confrontations and to ensure safety of airplanes," defence ministry spokesman Kim Min-seok told AFP on Sunday.
Earlier this week, US Vice President Joe Biden said China's announcement had caused "significant apprehension in the region".
He was speaking during a visit to China overshadowed by tensions raised by the announcement.