BBC Sounds, Music, radio, podcasts.

This year, children around the world have been able to track the progress of Father Christmas

as he makes his way from his home in the Arctic Circle, delivering presents all over the globe.

His journey is plotted on the American military's NORAD website.

But keeping tabs on Santa is not North American Aerospace Defense Command's main purpose.

The rest of the year, 24 hours a day, it watches the movement of ships, planes and submarines

and looks out for the first signs of missiles.

And one of the areas it keeps a close eye on is the Arctic.

That was true during the Cold War and War is rarely colder than at the North Pole,

and it's becoming true again now because the Arctic is changing

and in ways that create new possibilities and new threats.

So, what are those possibilities and what are those threats?

Step into the briefing room where a map of the far north has been pinned to the wall and together we'll find out.

First, what do we mean by the Arctic?

Who lives there and who owns it?

Jennifer Spence is the director of the Arctic Initiative

at the Belfast Centre for Science and International Affairs

at the Harvard Kennedy School.

What is the Arctic?

One of the important things I always like to think about,

because we often compare the Arctic and the Antarctic,

is the Arctic is actually an ocean covered in ice,

...