US Navy plans for 12 Columbia-class nuclear submarines could reduce launch capacity. Military leaders advocate for more boats to maintain deterrence.

Here’s what you’ll learn when you read this story: For the first time, China has outstripped U.S. nuclear-powered submarine production. U.S. plans to shore up an aging submarine fleet are delayed.

Chinese researchers have completed what they describe as a first deep-sea field test of a diamond-based quantum magnetometer, a device that could one day help detect the faint magnetic signatures of ...