I never thought that the Arctic, the vastly uninhabited chunk of mostly ice north of Alaska, could provide a source of conflict in the 21st century. But, then came along global warming and aggressive neighbors. As the ice is receding at a quicker than normal rate, open Arctic waters provide bordering nations with trade, tourist, and natural resources new possibilities (as well as strategic defense) that were not open before. Case in point, there is actually a Northwest Passage right now.
Now what problem could possibly occur when you have the bordering nations being the US, Canada, Denmark (they own Greenland), and Norway, all US allies? None, except that I am forgetting one, America's newest best friend- the Russian Federation! Russia, under former President and current Prime Minister Vladimir Putin, has been assertive in nationalistic pursuits now that they are flush with oil and gas revenues. Aside from invading Georgia, Russia recently planted a flag in the Arctic and claimed a large chunk of it for itself. Why do they want a chunk of ice? Because there is potentially more oil and natural gas underneath that was previously inaccessible.
Sadly, the US has been slow to counter this threat to our own strategic interests (remember that Russia borders us up there) by not expanding our Arctic fleet nor ratifying the Law of the Sea, which would allow the US to stake claims in the Arctic, the US is losing the opening salvos of a scramble for the Arctic. And while I don't think having Canada, Denmark, or Norway control the Arctic would be a bad thing, I do not want to see Russia suddenly get an Arctic empire. And if the US and its allies don't act soon, this could happen.