In recent weeks, NATO conducted its largest military exercises in decades in the frigid waters and icy mountains of Norway. But something odd happened. The GPS signals guiding ships, aircraft, tanks, trucks and troops started to fail. Civilian airliners, cars, trucks, cargo ships and smart phones operating in and around Norway and Finland experienced similar GPS jamming disruptions. Why? Russia is the chief suspect. It was riled by the scale and location of NATO’s Trident Juncture maneuvers — despite having itself conducted several massive military exercises in the Baltics recently. And Moscow is known to be avidly experimenting with ways to disrupt military forces — and the global economy — through sabotaging or destroying the now vital GPS navigation network.