The NATO exercise, Trident Juncture, concluded Sunday and involved some 50,000 personnel. It was billed as the alliance's most massive exercise since the Cold War. Non-NATO members Finland and Sweden took part in the exercise.

A spokesperson for the Norwegian ministry of defence acknowledged the jamming to CNN, which it said took place between October 16 and November 7.

"Norway has determined that Russia handled jamming GPS signals in the Kola Peninsula during Exercise Trident Juncture. Finland has expressed concern over possible jamming in Lapland", NATO spokesperson Oana Lungescu told CNN Wednesday.

"Given the civilian usage of GPS, jamming of this sort is dangerous, disruptive and irresponsible", she added.

A US defence official insisted that the jamming had "little or no effect" on US military assets during the NATO exercise.

Pentagon spokesman Eric Pahon told CNN in a statement:

"The US is keenly aware cyber-attacks, and electronic warfare are being used on and off the battlefield with alarmingly greater frequency and severity. We have experienced this in many areas where we operate, and we have observed the potentially devastating impact such measure could pose to civilian aviation. We are directly addressing these expanding threats, increasing our ability to deal with these challenges and developing new ways to defend against them."