The protest was conveyed by the ministry’s head of the international policy bureau to the military attaches stationed at the Chinese and Russian embassies in Seoul, the ministry said in a statement.
“The ministry expressed regret to both countries over the flight close to our airspace over sensitive areas without prior notice,” it said.
South Korea and Japan scrambled fighter jets when two Chinese and four Russian military planes flew over the sea between the two countries and entered their air defence zones.
The Air Defense Identification Zone is an area where countries may unilaterally demand that foreign aircraft take special steps to identify themselves, according to the International Civil Aviation Organization.
Moscow does not recognise Korea’s air defence zone. Beijing has said the zone is not territorial airspace and all countries should enjoy freedom of movement there.
