Russia’s Pacific Fleet said diesel-electric submarines from Russia and China have completed their first joint underwater patrol in the Asia-Pacific, expanding a defence partnership that until now had focused on surface and aerial operations. The mission started shortly after the two navies wrapped up the “Sea Interaction 2025” drills in the Sea of Japan and ran from 9 July to 4 August. Russia’s submarine Volkhov, escorted by the corvette Gromkiy and the rescue tug Fotiy Krylov, teamed with an unnamed Chinese boat to sail more than 2,000 nautical miles (about 3,700 kilometres) through the Sea of Japan and East China Sea before returning to Vladivostok. Moscow and Beijing described the patrol as a step toward deepening naval coordination, maintaining regional stability and protecting their maritime economic interests. Both capitals stressed that the operation “does not target any third party,” a message aimed at neighbouring states and the United States, whose forces routinely operate in the same waters. The underwater foray comes ahead of President Vladimir Putin’s trip to China for a Shanghai Cooperation Organisation summit and follows annual joint air and surface patrols launched in 2019. Analysts say the move underscores the growing strategic alignment between the two militaries as Russia looks eastward amid Western sanctions and China counters U.S.-led security groupings in the Indo-Pacific.