There have been fresh hints of that activity in recent weeks. In six days there have been six instances of damage or disruption to undersea cables in the Baltic Sea. The latest episode occurred on January 2nd, when a 65km-long cable to Lithuania was severed in Latvian territorial waters off Liepaja on the country’s west coast (see map). Latvian police boarded a suspect vessel—one of four that crossed the cable’s route on the day—and studied its anchor and logs, but found nothing incriminating. Repairs are likely to take one to two weeks. A few days earlier, on December 31st, Finnish...