News of the Healy vessel's trip came as two Russian mini-submarines started the first-ever dive 4,200 meters (14,000 feet) under the ice near the North Pole to take soil and fauna samples on the ocean floor, and back the country's claim to a vast swathe of the hydrocarbon-rich Arctic territory.
The Healy is one of the U.S.' four polar icebreakers. But the National Research Council last September urged the construction of two new icebreakers to replace the ageing Polar Sea and Polar Star "to project [the country's] active and influential presence" in support of its interests in the Arctic and the Antarctic.
Melting sea ice in the Arctic is opening new shipping routes and sparking economic activity, such as exploration for natural resources, the council's Congress-sponsored report said.
President George W. Bush has also urged the Senate to approve U.S. participation in the United Nations Convention on the Law of the Sea "to advance U.S. interests in the world's oceans."
"Joining [the convention] will serve the national security interests of the United States," Bush said in a May 15 statement, and "promote U.S. interests in the environmental health of the oceans and ... give the United States a seat at the table when the rights that are vital to our interests are debated and interpreted."
A UN commission is yet to rule on Russia's claim to 1.2 million sq kilometers (about 460,000 sq miles) of the territory - the underwater Lomonosov Ridge and Mendeleyev Ridges - which it says is the continuation of its continental shelf.
A U.S. survey suggests the Arctic seabed contains up to 25% of the world's oil and natural gas reserves, and other mineral riches, made accessible by the receding of the polar ice caused by global warming.