China Pairs Type 039B Yuan AIP Submarine with Russian Kilo-class in Rare Joint Naval Exercise.

China is deploying one of its most advanced Type 039B Yuan-class Air Independent Propulsion (AIP) submarines alongside a Russian Project 636.3 Kilo-class submarine during the Joint Sea-2026 naval exercise, a development that signals deeper Sino-Russian undersea military cooperation with growing implications for Indo-Pacific maritime security. As the participating naval forces transition from the exercise to joint patrols in the Pacific Ocean, the deployment highlights increasingly coordinated submarine operations that could complicate the U.S. Navy’s and allied forces’ ability to maintain undersea dominance across the region.

The pairing combines two of the most capable conventional submarines in Chinese and Russian service, strengthening interoperability in anti-submarine warfare, maritime strike missions, and submarine rescue operations. Beyond the exercise itself, the deployment reflects a broader trend toward closer operational integration between Beijing and Moscow, reinforcing their ability to project undersea power and challenge Western naval forces in strategically contested waters.

Related Topic: China Navy's Type 039C submarine reportedly undergoing sea trials

Chinese and Russian naval submarines are seen operating together during the Joint Sea-2026 exercise. (Picture source: CCTV Military, screenshot)

The exercise, launched on July 6, 2026, and hosted by the People's Liberation Army Navy (PLAN) in Qingdao, brings together ten Chinese and Russian naval units, including surface combatants, submarines, naval aviation, and support vessels. Live-fire scenarios include joint reconnaissance, air and missile defense, anti-surface strikes, and submarine rescue, demonstrating an operational focus on high-intensity maritime conflict rather than routine bilateral naval engagements.

Unlike previous editions of the Joint Sea series, this year's exercise places particular emphasis on underwater warfare, one of the most strategically significant domains in modern naval competition. The combined deployment of China's advanced Type 039B and Russia's Improved Kilo-class submarine demonstrates that both navies are increasingly willing to integrate sensitive undersea capabilities into bilateral training, reflecting a higher level of operational confidence and interoperability than seen in earlier exercises.

The PLAN's Type 039B is among China's most advanced conventionally powered attack submarines. Equipped with an Air Independent Propulsion (AIP) system, it can remain submerged for significantly longer periods than conventional diesel-electric submarines, reducing the need to snorkel and making detection more difficult. Combined with improved acoustic quieting, modern sonar arrays, and the ability to launch heavyweight torpedoes and anti-ship cruise missiles, the Type 039B is optimized for sea-denial missions, intelligence collection, and operations inside contested waters such as the Taiwan Strait and the South China Sea.

Joint Sea-2026 brings together warships, submarines, naval aviation, and support vessels in realistic combat training. (Video footage: Russian MoD)

Russia's Project 636.3 Improved Kilo-class remains one of the world's quietest diesel-electric attack submarines. Armed with heavyweight torpedoes and Kalibr land-attack and anti-ship cruise missiles, it provides the Russian Navy with a versatile precision-strike capability while offering extensive operational experience in stealth submarine operations. Training with the PLAN allows Russian crews to exchange tactics with one of the world's fastest-growing submarine forces while exposing Chinese operators to decades of Russian expertise in conventional undersea warfare.

Although neither submarine matches the speed, endurance, or global reach of U.S. Navy Virginia-class nuclear-powered attack submarines, their operational role is fundamentally different. Conventional AIP submarines are exceptionally difficult to detect in shallow coastal waters, making them particularly effective in chokepoints and littoral environments surrounding Taiwan, the East China Sea, and the South China Sea. These are precisely the areas where the U.S. Navy and allied forces would likely operate during a regional crisis, increasing the importance of anti-submarine warfare capabilities for the United States, Japan, Australia, and other Indo-Pacific partners.

The exercise also includes one of the most technically demanding aspects of submarine operations: joint submarine rescue. Conducting bilateral rescue drills requires compatible procedures, specialized rescue vessels, deep-diving systems, and coordinated command structures. Such cooperation demonstrates growing trust between the Chinese and Russian navies and improves their ability to sustain submarine operations during prolonged deployments.

Chinese officials stated that the sea phase included live-force and live-fire training covering joint reconnaissance, integrated air defense, anti-surface warfare, and coordinated command-and-control operations. The scenarios are designed to replicate realistic combat conditions and improve the participating forces' ability to respond collectively to complex maritime security threats.

Before moving to sea, both navies conducted extensive operational planning in Qingdao through tabletop exercises, professional seminars, reciprocal ship visits, and mission coordination meetings. These activities helped synchronize tactical procedures and communications before transitioning to live operational training.

Following the completion of the exercise, participating Chinese and Russian naval units are continuing joint patrols in the Pacific Ocean, extending military cooperation beyond scheduled drills to coordinated operational deployments. Such patrols enhance both navies' experience in long-range maritime operations while reinforcing their combined presence in strategically important waters stretching from the East China Sea into the broader Western Pacific.

Now in its twelfth edition since launching in 2012, the Joint Sea series has evolved from a diplomatic confidence-building exercise into an increasingly sophisticated military training program integrating surface combatants, submarines, naval aviation, and logistics forces. The inclusion of advanced underwater assets reflects a broader trend toward deeper operational integration between Beijing and Moscow as both countries seek to improve their ability to operate together in contested maritime environments.

For U.S. defense planners and NATO navies, the significance of Joint Sea-2026 extends well beyond a bilateral exercise. While the United States retains a decisive advantage in nuclear-powered submarines and global undersea surveillance, expanding cooperation between the PLAN and the Russian Navy is steadily improving China's proficiency in submarine operations, command and control, and coordinated maritime warfare. As Beijing continues to modernize its submarine fleet and Russia contributes decades of operational experience, these exercises could gradually complicate allied anti-submarine warfare planning across the Indo-Pacific, particularly in any future contingency involving Taiwan or freedom-of-navigation operations in the Western Pacific.

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Written by Alain Servaes – Chief Editor, Army Recognition Group
Alain Servaes is a former infantry non-commissioned officer and the founder of Army Recognition. With over 20 years in defense journalism, he provides expert analysis on military equipment, NATO operations, and the global defense industry.