How Vulnerable Are Undersea Cables That U.S. Says Russia Is Tracking?

Announcing fresh sanctions against Russia this week, the U.S. Treasury Department accused Moscow of “tracking undersea communications cables” and imposed punitive measures on a St. Petersburg firm that it says provided underwater diving equipment to Russia’s Federal Security Service (FSB).

The announcement followed warnings by U.S. and other Western officials about Russian activities in recent years near undersea cables that serve as conduits for nearly all global telecommunications data.