The Atlantic Council’s writeup of the Russian threat to our undersea comms includes this bit:
Russia is also building an undersea unmanned drone capable of carrying a small, tactical nuclear weapon to use against harbors or coastal areas, American military and intelligence analysts said.
Admiral Ferguson said that as part of Russia’s emerging doctrine of so-called hybrid warfare, it is increasingly using a mix of conventional force, Special Operations mission and new weapons in the 21st-century battlefield.
“This involves the use of space, cyber, information warfare and hybrid warfare designed to cripple the decision-making cycle of the alliance,” Admiral Ferguson said, referring to NATO. “At sea, their focus is disrupting decision cycles.”