South Korea's defense ministry called in Russia's defense attache in Seoul on Thursday to protest the entry of Russian warplanes into Seoul's air defense identification zone (KADIZ) for the eighth time in 10 days.

Axar.az reports citing Yonhap, earlier in the day, multiple Russian military aircraft entered the KADIZ over the East Sea, flying as close as 20 kilometers to South Korea's airspace without responding to Seoul's communication attempts.

In response, the South Korean military scrambled its fighter jets, according to the ministry.

It marked the eighth time since March 11 that Russian warplanes had entered the KADIZ without prior notice, it said.

The ministry said it called in Col. Nikolai Marchenko, a military attache at the Russian Embassy in Seoul, to protest the move and urge preventative measures.

The air defense zone is not territorial airspace but is delineated to call on foreign planes to identify themselves so as to prevent accidental clashes.

The latest incident took place only days after multiple Russian warplanes entered the KADIZ on Saturday while they were conducting air drills, according to the Joint Chiefs of Staff.