Multiple Russian military planes entered the Korea Air Defense Identification Zone(KADIZ) for the second time in five days, prompting Seoul to lodge a formal protest. 

According to the defense ministry, the Russian aircraft entered KADIZ over the East Sea Thursday morning before leaving the area.

There was no violation of South Korean airspace.

The South Korean military detected the aircraft before their entry and deployed Air Force fighter jets to swiftly respond and prevent any potential incidents.
 
Several Russian military planes had previously entered KADIZ over the East Sea last Saturday before departing.

The military protested over the phone after the Russian side confirmed the aircraft were conducting training and had no intention of violating territorial airspace.

After the Russian side failed to provide immediate verification, the ministry summoned Nikolai Marchenko, a military attaché at the Russian Embassy in Seoul, to protest the KADIZ entry. 

An air defense identification zone is a region where a country seeks to identify, locate, and control foreign military aircraft approaching its airspace, distinct from sovereign airspace.