MOSCOW — A Russian expedition led by a nuclear-powered icebreaker reached the North Pole on Wednesday on a mission to send two mini-submarines to the polar seabed.
The expedition, which would be the first to reach the polar sea bottom 2.6 miles below the Arctic Ocean surface, is seen as part of an effort to bolster Russian claims to about 460,000 square miles of sea floor believed to hold lucrative deposits of oil and natural gas. Global warming, which has reduced the size of the Arctic ice pack, has fueled interest in exploiting the area's energy resources.
"Our main aim is to remind the whole world that Russia is a great polar and scientific research power," Artur Chilingarov, a veteran polar explorer due to pilot one of the mini-subs, wrote in an e-mail from the expedition's research ship.
"You can understand that to touch the seabed at such depth is something like taking the first step on the moon," said Chilingarov, who is also a deputy speaker of the lower house of parliament.
The two-vessel expedition carrying the mini-subs embarked from Murmansk, on the Barents Sea, on July 24.
Researchers in the mini-submarines, equipped with video cameras, plan to spend an hour on the ocean floor, where they will place a Russian flag, leave a message to future generations in a capsule, and take soil and biological samples from the seabed.
The dive began about 8 a.m. today Moscow time and was scheduled to last about eight hours, state-run television reported from the North Pole.
The mini-subs are expected to return to the same hole through which they descended. Any miscalculation, however, could leave the subs trapped beneath the ice pack.
"This is a serious, risky operation," Sergei Balyasnikov, a spokesman for the Arctic and Antarctic Research Institute in St. Petersburg, told the Russian news agency RIA Novosti. The institute, which has scientists along on the mission, reported that weather conditions were expected to be favorable for today's dive, with weak winds and visibility up to 12 miles.
Dmitry Oreshkin, a political analyst at the Russian Academy of Sciences' Institute of Geography, said the expedition was mostly "public relations and propaganda" meant to emphasize Russia's maritime resurgence.
Russian authorities were embarrassed in 2000 by the disaster that struck the nuclear-powered submarine Kursk, which sank in the Barents Sea after a series of explosions. Several of its 118 crew members apparently survived the blasts, but died while officials delayed calling for international aid to rescue the vessel.
In 2005, a mini-submarine carrying seven crew members was rescued after becoming entangled in cables and fishing nets in the Bering Sea.
"Our authorities want to show their own people, 'Look, we are still a great sea and polar superpower,' " Oreshkin said. "It is something to the effect of, 'The Americans were the first on the moon, and now we will be the first under water.' "
Placing the Russian flag on the North Pole ocean floor is intended to have symbolic meaning, and would have no legal effect on Russia's claim to vast areas of the Arctic Ocean.
Under the U.N. Convention on the Law of the Sea, that claim depends on whether geologists can prove that the continental shelf extends from Russia's coast to the pole. The United States has not ratified the convention, which some argue puts it at a disadvantage in competition for resources.
The part of the Arctic Ocean claimed by Russia could hold oil and gas deposits equal to about 25% of the world's current oil and gas reserves, RIA Novosti said.
The technical challenges of exploiting such potential energy deposits are enormous, largely because of the threat that shifting ice would pose to platforms and vessels.
Russian scientists say the underwater Lomonosov Ridge extends from Siberia to the pole, and that this backs up Moscow's territorial claim. Some experts, however, say that Denmark could make a similar claim, because the ridge runs past the pole and close to the Danish territory of Greenland.
The researchers in the mini-subs will attempt to gather additional evidence concerning the Lomonosov Ridge to help back up the territorial claim, Rossiya television said.
Under international law, the five countries with coastal territory inside the Arctic Circle, which are Russia, the United States, Canada, Denmark and Norway, can claim an economic zone extending 200 miles into the Arctic Ocean from their coasts.
Canadian Prime Minister Stephen Harper announced last month that his country would spend $6.7 billion to purchase six to eight Canadian-made patrol ships that can operate in ice up to about 3 feet thick.
"The world is changing," Harper said in announcing the plan. "The ongoing discovery of the north's resource riches, coupled with the potential impact of climate change, has made the region an area of growing interest and concern."
Oreshkin expressed skepticism that Russia would succeed in its effort to use the geography of the Lomonosov Ridge to bolster its territorial claims. Iceland, he said, is connected to another ridge that stretches between the mid-Atlantic and the Norwegian Sea, and could claim control of a vast strip, he said.