Seoul has complained to the defense attachés of the two countries about the intrusion of Chinese and Russian warplanes into South Korea’s Air Defense Identification Zone (Cadiz).

The South Korean capital, Seoul, alleged that seven Russian and two Chinese military aircraft briefly entered the air defense identification zone. They deployed multiple warplanes as soon as the matter came to their attention.

South Korea is said to have sent these warplanes as a strategic measure to deal with any unexpected situation. However, Seoul also said that the Russian and Chinese planes did not violate South Korea’s airspace.

According to international law, the air defense identification zone is not part of any country’s sovereign airspace, but some countries have rules for foreign aircraft in the zone to declare their identities.

In March of this year, Seoul sent warplanes after a similar Russian warplane entered the South Korean zone.

The Russian bombers flew near the islands of Ulleung and Dokdo, while the Chinese bombers flew near the Edo region, according to local media, citing South Korea’s Joint Chiefs of Staff.

The two countries’ planes later flew together in the airspace near Japan’s Tsushima island.

While complaining about the Russian-Chinese plane incursion on Wednesday, South Korea’s Defense Ministry said, “Our military will actively respond to the activities of neighboring countries’ aircraft in the Air Defense Identification Zone (CADIZ) in accordance with international law.”

China confirmed on Wednesday that its air force had conducted joint patrols with Russia in the East China Sea and the western Pacific Ocean.

The patrols were part of the annual China-Russia cooperation plan, which aims to address regional challenges and maintain peace and stability, according to a Chinese national defense spokesman.