Tension at Norway's icy border with Russia as military presence increases

American Marines, training in freezing cold temperatures in northern Norway....

The troops are part of a contingent of 650 Marines staging a recent joint military exercise with 3,000 soldiers from their fellow NATO member, Norway, at a time when both NATO and Russia have increased their military presence in the Arctic.

Just a few hundred kilometers away, Russia is modernizing its forces on the Kola Peninsula, home to its Northern Fleet.

And according to intelligence sources cited by Norwegian media, Russia also recently staged a major submarine exercise in the North Atlantic.

NORWEGIAN BORDER RANGER, JORGEN AAS, POINTING OUT THE RUSSIAN BORDER, SAYING (English): ''Russia is that way (points) but it also goes north.''

(SOUNDBITE) (English) NORWEGIAN BORDER RANGER, JORGEN AAS, SAYING:

"We are keeping watch at Russia, 24/7 and it's because this is the outer border of Schen gen."

It's unsettling Norwegians - not least in the town of Kirkenes - which for three decades has been trying to foster cooperation with Russia.

Residents are able to cross the border quickly without a visa -- it's great to buy cheap gas, they say.

And many Russians have moved across the border for work.

The municipality's mayor describes Kirkenes as a ''Russian town in Norway.''

(SOUNDBITE)(English) MAYOR OF SOER-VARANGER MUNICIPALITY, WHICH INCLUDES KIRKENES, RUNE RAFAELSEN, SAYING, ON MILITARY BUILD-UP:

"I am not a person who is crying out for more tanks and cannons and weapons along the border, but I have full respect and I respect the Norwegian government how they are considering what is needed for the military. But of course, low tension is the best."

Russia has decried the presence of the U.S. Marines at Norwegian bases - which it sees as yet another security challenge.

But Norway's government worries about Moscow's intentions -- particularly after Russia annexed Crimea from Ukraine in 2014.