Chinese J-20 stealth fighter flew unnoticed through the Tsushima Strait - an alert for the air defenses of Japan and Korea

 China's fifth-generation Chengdu J-20 stealth fighter reportedly flew unnoticed for the first time through the Tsushima Strait, a strategically important maritime corridor between Japan and South Korea. This strait is located in the air defense zones of both countries and is covered by radar systems, including the American THAAD missile defense systems. However, according to the Chinese state television channel CCTV and a number of international sources, neither Japan, South Korea, nor the United States have publicly reported on the recording of this flight, which indicates possible serious gaps in regional radar defense.

Analysts note that the J-20 used a low—altitude flight profile of about 30-100 meters above the water surface, which significantly reduces radar visibility due to a reflective surface of only 0.1–0.3 m2, making it virtually invisible to air defense systems on land and at sea. According to experts, the key J/FPS-3UG long-range radar on Mount Seburiyama in Japan was unable to detect this fighter, partly due to the lack of long-range control aircraft at that time.

This undetected overflight has caused concern in the region, as the Tsushima Strait is an important military—strategic hub providing communications between the East China Sea and the Sea of Japan, controlled by Japan, South Korea and supported by the United States. The flight of the J-20 demonstrates China's capabilities in the field of stealth technology and signals the need to modernize and improve the effectiveness of air defense and early warning systems in East Asia.

In addition to a political show of force, such a maneuver can be considered as a test of the tactical capabilities of the Chinese fighter in real conditions of radar counteraction and a check of vulnerabilities in the defense systems of neighboring countries. The absence of official denials or reactions from Japan and Korea may mean either the fact of an unnoticed flight, or caution in aggravating the situation.

Overall, this incident underscores the growing importance of modernizing regional defense infrastructure and the need for enhanced cooperation between Japan, South Korea and their allies to close gaps in the radar system and increase preparedness to respond to such threats.

 J-20