Two Russian TU-95 nuclear bombers entered Korea's Air Defense Identification Zone near Dokdo and the submerged reef of Ieo on Monday without permission.
The identification zone is airspace which foreign military aircraft need approval to enter 24 hours in advance. But such zones are not governed by any international treaties and respecting them is a matter of discretion.
One Soviet-built airborne early-warning aircraft A-50 was apparently flying in the northeastern part of the East Sea. The Korean Air Force scrambled fighter jets and issued verbal warnings.
Japanese fighter jets were also dispatched, Japan's Sankei Shimbun reported. The air defense identification zones of Korea, China and Japan overlap around Ieo.