By Paul Reynolds
World Affairs correspondent, BBC News website
The Russians are leading a new "gold rush" in the high north, with a bold attempt to assert a claim to oil, gas and mineral rights over large parts of the Arctic Ocean up to the North Pole.
New "goldminer": Artur Chilingarov
Russia's most famous explorer, Artur Chilingarov, complete with nautical beard, led the expedition to plant the Russian flag in a capsule on the ocean seabed under the pole itself.
"The Arctic is Russian," Chilingarov said earlier. "We must prove the North Pole is an extension of the Russian coastal shelf."
Russia is claiming that an underwater mountain known as the Lomonosov Ridge is actually an extension of the Russian landmass.
This, it argues, justifies its claim to a triangular area up to the pole, giving it rights under the United Nations Law of the Sea Convention.
Under Article 76 of the convention, a state can claim a 200 nautical mile exclusive zone and beyond that up to 150 nautical miles of rights on the seabed. The baseline from which these distances are measured depends on where the continental shelf ends.
Russia lodged a formal claim in 2001 but the UN's Commission on the Limits of the Continental Shelf told it to resubmit the claim. The flag-planting can be seen as a symbolic gesture in support.
At the same time, other states are acting to protect their interests in the Arctic. Canada is planning to build up to eight new patrol ships and the US Congress is considering a proposal to build two new heavy polar ships.
The rush for the Arctic has become more frenzied because of the melting of parts of the polar ice cap, which will allow easier exploration, and by the urgent need for new sources of oil and gas. A new sense of nationalism is also evident in Russia.
Shaded area on Russian map shows claim up to North Pole
The ice thaw is predicted by a team of international researchers whose Arctic Climate Impact Assessment suggested in 2004 that the summer ice cap could melt completely before the end of this century because of global warming.
If the ice retreats, it could open up new shipping routes and new areas where natural resources could be exploited.
The US Geological Survey estimates that a quarter of the world's undiscovered energy resources lies in Arctic areas.
At the moment, nobody's shelf extends up to the North Pole so there is an international area around the Pole administered by the International Seabed Authority from Kingston, Jamaica.
But quite apart from the Russian claim there are multiple other disputes.
The US and Canada argue over rights in the North-west Passage, Norway and Russia differ over the Barents Sea, Canada and Denmark are competing over a small island off Greenland, the Russian parliament is refusing to ratify an agreement with the US over the Bering Sea and Denmark is claiming the North Pole itself.
North Pole solutions
The five countries involved are considering two other potential ways of sharing the region, in which all the sea would be divided between them.
The "median line method", supported by Canada and Denmark, would divide the Arctic waters between countries according to their length of nearest coastline. This would give Denmark the Pole itself but Canada would gain as well.
The "sector method" would take the North Pole as the centre and draw lines south along longitudes. This would penalise Canada but Norway and, to a lesser extent, Russia, would gain.
One major problem is that the United States has not ratified the 1982 UN convention, largely because senators did not want to have international restrictions placed on American actions.
However, in May 2007, Senator Richard Lugar, a senior Republican, pleaded for ratification in the light of the Russian moves, saying that an American voice was needed at the negotiating table.
RUSSIA'S ARCTIC CLAIM
1) North Pole: Russia leaves its flag on the seabed, 4,000m (13,100ft) beneath the surface, as part of its claims for oil and gas reserves
2) Lomonosov Ridge: Russia argues that this underwater feature is an extension of its continental territory and is looking for evidence
3) 200-nautical mile (370km) line: Shows how far countries' agreed economic area extends beyond their coastline. Often set from outlying islands
4) Russian-claimed territory: The bid to claim a vast area is being closely watched by other countries. Some could follow suit