The aircraft entered the Korea Air Defense Identification Zone (KADIZ) off its east coast between 11:53 a.m. (0253 GMT) and 12:10 p.m. and then left the area, South Korea’s Joint Chiefs of Staff (JCS) said in a statement.
The planes did not violate South Korea’s territorial airspace, the military said.
An ADIZ is usually an area where countries may unilaterally demand that foreign aircraft take special steps to identify themselves, according to the International Civil Aviation Organization.
That is different from a nation’s airspace, which usually means the space above its territory, extending 12 nautical miles away from its coastline.
Unlike airspace, there are no international laws that govern air defence zones. 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.
