China is talking about putting the new ultra quiet propulsion system on new nuclear-powered type 095 attack submarines and Type 096 ballistic missile submarines.

A rim-driven pump-jet has a ring-shaped electrical machine inside the pump-jet shroud, which turns the vane rotor inside the pump-jet cavity to create thrust. The design reduces noise by removing the shaft and also creating smaller water bubbles , Making it even quieter.

Modern American and British submarines already use pump-jet propulsion, but Koh said the technology had not been adopted more widely because its design was complex, and just a few countries could support the technology with "a good deal of funding and technical expertise".