In 1954, the United States introduced the world to the first nuclear submarine, the USS Nautilus (SSN-571). Ever since, each new U.S. Navy sub has been nuclear-powered. They make up a massive submarine force consisting of more than 70 active vessels, so the Navy puts a lot of resources into their operation. Over the years, the U.S. has lost two nuclear submarines with all hands, the USS Thresher (SSN-593) and the USS Scorpion (SSN-589), though neither succumbed to enemy action. Still, that doesn't mean that there aren't any weapons capable of sinking a U.S. nuclear submarine. In fact, there are several that…