Russia warplanes spotted entering Seoul’s defense zone.

In response to reports that Chinese and Russian aircraft were spotted near their countries on Thursday, the governments of South Korea and Japan scrambled fighter jets.

According to the Joint Chiefs of Staff of the South Korean armed forces, the country scrambled fighter jets after two Chinese and four Russian military planes entered its air defense zone.

Separately, according to Japan’s Defense Ministry, Japan’s bombers and fighters, which were participating in joint exercises with Chinese and Russian aircraft on Thursday, had scrambled jets to monitor the activities.

Among the aircraft involved were the Chinese H-6, J-16, Y-8, as well as Russian Tu-95 and Su-35 aircraft. The planes were spotted flying toward East China Sea through the channel between Japan and South Korea, according to Japan’s Ministry of Foreign Affairs.

As reported by the South Korean military, the aircraft entered the Korea Air Defense Identification Zone off its east coast between 11:53 a.m. in the morning and 12:10 in the afternoon South Korean time and then left the area shortly afterward.

As far as the South Korean military is concerned, the planes did not violate the country’s territorial airspace, which is protected by international law. In contrast, a defense zone is different from a nation’s territorial airspace, which is usually defined as the space over that nation’s territory that extends 12 nautical miles away from its coast.

In accordance with Reuters, the International Civil Aviation Organization said there was no international law that governs air defense zones, which are an area of the sky where countries themselves can individually and unilaterally require foreign aircraft to provide certain information in order to identify themselves.