Japan tracks Chinese Dongdiao spy ship with missile destroyer escort near its coast.

Japan’s Ministry of Defense confirmed that a Chinese intelligence ship and destroyer transited the Osumi Strait into the Pacific on October 18–19, shadowed by Japan’s maritime forces. The move reflects Beijing’s expanding surveillance footprint and Japan’s heightened readiness near its southern islands. The

Japan’s Ministry of Defense Joint Staff displayed, on October 20 2025, that the Maritime Self-Defense Force confirmed a Chinese Dongdiao-class intelligence collection ship, hull number 795, and a Luyang III-class guided-missile destroyer, hull number 131, transiting east through the Osumi Strait into the Pacific on October 18–19. JMSDF assets, including destroyer Amagiri, missile boat Otaka and P-1 maritime patrol aircraft, shadowed the formation and gathered imagery. The Dongdiao was first tracked roughly 80 kilometers west of Kuchinoerabujima on October 18, while the destroyer was seen about 40 kilometers west in the early hours of October 19. 
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A Chinese Type 815 Dongdiao-class intelligence ship and a Luyang III-class destroyer transit Japan’s Osumi Strait toward the Pacific, shadowed by JMSDF vessels and aircraft, in a clear show of Beijing’s expanding blue-water surveillance operations (Picture source: Japan MoD).

The centerpiece of this sortie is the Type 815 Dongdiao, the PLAN’s workhorse for electronic intelligence. Open sources place the class at about 6,000 tons full load, roughly 130 meters long with a 16-meter beam, cruising near 20 knots. It is fitted with prominent spherical radomes, satellite dishes and linear antenna arrays used to capture communications and electronic emissions across wide bands, with a hangar and deck space for a light helicopter to extend collection range. Armament is minimal, typically light guns for self-defense, underscoring its non-combat ISR role. U.S. Navy recognition materials identify Dongdiao variants across multiple fleets, confirming the class as the PLAN’s standard AGI for blue-water monitoring and missile telemetry support.

The Dongdiao maps the region’s electronic order of battle. From the Osumi approach it can sample Japanese and allied radar modes, data links and communications associated with air defense sites in Kyushu, JMSDF picket ships, and U.S. assets transiting to the Philippine Sea. The ship’s large radomes indicate capacity for satellite downlink interception and ballistic-missile test tracking, allowing the PLAN to refine counter-measure libraries and improve cueing for long-range fires. Its low signature and long on-station endurance make it ideal for camping outside exercises to vacuum up emissions without crossing legal red lines.

The Luyang III-class destroyer provides the protection. At roughly 7,000 tons, the Type 052D mounts a universal 64-cell vertical launcher capable of carrying HHQ-9B area-air-defense missiles, YJ-18 anti-ship cruise missiles, CJ-10 land-attack weapons and CY-5 anti-submarine rockets. A Type 346A AESA radar suite, towed and variable-depth sonar, a 130 mm main gun, and close-in defenses round out a multi-mission package that can screen the AGI against aircraft, submarines and surface threats while projecting layered fires. Tactically, the pairing lets the Dongdiao loiter where the emissions are rich, while the 052D acts as escort and deterrent, extending air and ASW cover and complicating any attempt to harass the collector.

This October transit fits a familiar Chinese pattern of pushing intelligence platforms through Japan’s straits to the open Pacific, normalizing presence beyond the first island chain and collecting against allied operations. The Joint Staff’s readout notes routine but firm JMSDF surveillance, with destroyers, missile boats and P-1 aircraft maintaining contact and documenting the operation. The timing intersects with a more muscular Japanese posture, from standing up the Joint Operations Command in March 2025 to deeper U.S. integration and expanded readiness across the Nansei islands. Tokyo’s latest public assessments also warn that China’s rapid military expansion and sustained far-seas activities are reshaping the security picture in the East China Sea and Philippine Sea, reinforcing the need for persistent maritime ISR and air defense investments.

Beijing has three goals with such maneuvers: first, data, as emissions captured near Kyushu help tune sensors and missiles for potential contingencies. Second, signaling, as the PLAN shows it can move mixed packages through Japanese chokepoints at will while staying within international law. Third, normalization, as repeated transits erode the perception that these waters are exclusively an allied operating space. For Japan, the answer remains transparency and presence, which is exactly what the JMSDF executed over October 18–19, by documenting the ships and reporting the information collected.

Written by Evan Lerouvillois, Defense Analyst, Army Recognition Group.

Evan studied International Relations, and quickly specialized in defense and security. He is particularly interested in the influence of the defense sector on global geopolitics, and analyzes how technological innovations in defense, arms export contracts, and military strategies influence the international geopolitical scene.