South Korea said on Tuesday that Russian planes entered its air defense identification zone without prior notice, the Yonhap news service reported, citing the country’s military.

The air defense identification zone expands beyond South Korea’s territory, also covering international airspace. The South Korean military require aircraft to give them a notice before entering the identification zone and notify them about the purpose of the flight.

Usually, if that doesn’t happen, the country scrambles its air force jets for interception, even if South Korean airspace wasn’t breached.

Moscow earlier said that the air defense identification zone was established by Seoul unilaterally and isn’t binding for other states. Russian