In February 1992, just months after the Cold War ended, the U.S. Navy’s USS Baton Rouge, a Los Angeles-class submarine, collided with Russia’s Sierra-class Kostroma near the Severomorsk naval base. The collision,

China’s naval buildup now includes a new class of attack submarine that employs both conventional and nuclear propulsion, according to defense officials.

In May 1969, the USS Guitarro, a Sturgeon-class nuclear-powered submarine, sank while under construction at the Mare Island Naval Shipyard due to human error. -Two teams of civilian engineers were working on the sub’s ballast tanks without coordinating,