China's primary conventional attack submarine with indigenous Stirling air-independent propulsion — a quiet, multi-week-endurance boat built for regional sea denial, and the platform behind Beijing's push into the submarine export market.
China's first credible sea-based nuclear deterrent — a nuclear-powered ballistic-missile submarine carrying up to 12 JL-2 or JL-3 SLBMs, fielding six boats for near-continuous patrols.
Russia's troubled Project 677 diesel-electric attack submarine — a mono-hull design intended to replace the Improved Kilo with Kalibr capability and planned air-independent propulsion, but plagued by decades of delays and an absent AIP system.
Russia's most modern nuclear attack submarine — a multirole SSGN carrying Kalibr, Oniks, and Zircon cruise missiles in vertical silos, and the quietest Russian submarine design to date, assessed as comparable to US Seawolf/Virginia generation.
Germany's pioneering fuel-cell AIP attack submarine — the ultra-quiet Type 212A, now evolving into the larger Type 212CD for North Atlantic/Arctic operations, operated by Germany, Italy and (on order) Norway.
Satellite imagery has caught a previously unreported Chinese submarine with no conning tower, the newest entry in a build rate Western navies cannot match.