Submarines are primarily valued for their ability to hide. The assurance that submarines will likely survive the first missile strike in a nuclear war and thus be able to respond by launching missiles in a second strike is key to the deterrence strategy known as mutually assured destruction. Any new technology that can make the oceans effectively transparent, making it trivial to spot lurking submarines, could undermine world peace. For nearly a century, naval engineers have striven to develop ever faster and quieter submarines. But they have worked just as hard on advancing a wide range of radar, sonar and other technologies designed to detect, target and eliminate enemy submarines.

The balance seemed to shift with the advent of nuclear-powered submarines in the early 1960s. In a 2015 study for the Center for Strategic and Budget Assessment, Bryan Clark, a naval specialist now at the Hudson Institute, noted that the ability of these ships to remain submerged for long periods of time made them “nearly impossible to find with active radar and sonar.” But even these stealthy subs produce subtle, very low-frequency noises that can be picked up from afar by networks of acoustic mounted on the seafloor.

And now the game of submarine hide-and-seek may be reaching the point where submarines can no longer evade detection and simply disappear. It may arrive as early as 2050, according to a recent study by the College of National Security at the Australian National University in Canberra.

This moment is particularly significant because the enormous costs required to design and build a submarine are destined to stretch out for at least 60 years. A submarine entering service today should still be in service in 2082. Nuclear-powered submarines, such as the Virginia-class fast-attack submarine, cost an estimated $2.8 billion each, according to the US Congressional Budget Office.