Tromso, Norway --

U.S. Secretary of State Hillary Rodham Clinton on Saturday ventured north of the Arctic Circle and urged international cooperation in a region that could become a new battleground for natural resources.

On her trip to the northern Norwegian city of Tromso, she conveyed that message of working together in one of the world's last frontiers of unexplored oil, gas and mineral deposits. The region is becoming more significant as melting icecaps accelerate the opening of new shipping routes, fishing stocks and drilling opportunities.

To safely tap the riches, the United States and other countries near the North Pole are trying to cooperate to combat harmful climate change, settle territorial disputes and prevent oil spills. At the least, the United States and the other Arctic nations hope to avoid a confrontational race for resources.

Officials say the picture looks more promising than five years ago, when Russia staked its claim to supremacy in the Arctic and its $9 trillion in estimated oil reserves by planting a titanium flag on the ocean floor. The United States does not recognize the Russian assertion and has its own claims, along with Denmark, Norway and Canada.

Moscow has eased tensions by promising to press any claims through a U.N. process. But Washington has yet to ratify the 1982 Law of the Sea treaty regulating the ocean's use for military, transportation and mineral extraction purposes. With 160 countries having signed on, the Obama administration is making a new push for Senate approval. Refusal puts the United States at risk of being excluded from the resources.

Arguing for its ratification at a recent Senate hearing, Clinton said the treaty would offer the United States oil and gas rights some 600 miles into the Arctic.

On Saturday, in the eight-nation Arctic Council's home city, she stressed that the international agreement "sets down the rules of the road that protect freedom of navigation and provides maritime security, serving the interest of every nation that relies on sea lanes for commerce and trade."