SOSUS, an acronym for SOund SUrveillance System, was a chain of underwater listening posts located across the northern Atlantic Ocean near Greenland, Iceland and the United Kingdom—the so-called GIUK gap. It was originally operated by the U.S. Navy for tracking Soviet submarines, which had to pass through the gap to attack targets in the Atlantic. Other locations in the Atlantic and Pacific Ocean also had SOSUS stations installed. It was later supplemented by mobile assets such as SURTASS… (More on Sosus)