U.S. nuclear submarine cruised through the Arctic Ocean last month -- probably passing through Canadian territorial waters -- but the federal government is refusing to say whether it gave permission for the voyage.

However, experts say it is highly unlikely Canada was even notified of the USS Charlotte's northern tour, which included a Nov. 10 stop at the North Pole, because it has no way of tracking what goes on beneath the Arctic ice.

And that could threaten Canada's claim to hundreds of thousands of square kilometres of the North, including the Northwest Passage route across the Arctic, said Michael Byers, who holds the Canada research chair in global politics and international law at the University of British Columbia.

"This is very important -- it's crucial," he said. "Any unauthorized passage could have a serious effect on our claim."

Prof. Byers said potentially lucrative oil and gas resources off the Queen Elizabeth Islands could slip out of Canadian control if foreign navies are operating in the Arctic without our permission. "The fact of the matter is that we've spent nothing on Arctic sovereignty over the past 20 years."

Pierre Leblanc, a retired colonel and former commander of the Canadian Forces' northern command, said foreign submarines have been travelling through the Canadian Arctic for decades, but the federal government usually finds out about it only by accident.

He said the nations controlling the submarines -- the Americans, British and French -- usually do not tell Canada when their vessels enter the Arctic. "We're relying on their goodwill to know if they're in our waters or not."