The British military discovered the sensors after a number of them washed ashore. Moscow is trying to collect intelligence on the UK's four Vanguard submarines, which carry nuclear missiles. At least one of the submarines is at sea as part of Britain's continuous at-sea deterrent. The Kremlin has a fleet of specialist submarines which are reported to be better equipped than Britain and NATO in terms of both seabed warfare and espionage. Russia has been stepping up surveillance and sabotage of underwater internet connections, energy pipelines, and military cables, which are key to the West. In 15 months, there have been at least 11 internet cables that have suffered damage in the Baltic Sea, partly because anchors have been dragged across the seabed by ships. Below is one of Britain's four Vanguard nuclear submarines, HMS Vigilant, at a naval base in Scotland. (Credit: James Glossop / AFP)