Diesel engines need oxygen, so how do submarines use them underwater?

Diesel engines cannot work without oxygen, so how do diesel submarines operate when they're underwater? Their propulsion ...
The National Interest on MSN

Japan is becoming a submarine powerhouse

Japan now operates five cutting-edge Taigei-class submarines, in addition to its 12 Soryu-class and 6 Oyashio-class vessels.

China is moving toward all-nuclear submarine construction in a major strategic shift, US Navy intel chief says

Most of China's submarine fleet is diesel-electric, but Beijing is ramping up production of nuclear-powered classes.
Janes

Japan commissions fifth Taigei-class submarine

Japan has commissioned its fifth Taigei-class diesel‑electric attack submarine, JS Chogei. The submarine was formally ...
Zawya

Iran claims to have best electronic diesel submarines in the world

01 March 2012 Iran has the best electronic diesel submarines in the world, Lieutenant Commander of the Iranian Army's Self-Sufficiency Jihad Rear Admiral Farhad Amiri said, Fars reported. Speaking to ...