Canadian presence in the Arctic could cost the Canadian military as much as $843 million annually, says a series of internal Defence Department cost estimates.

The bill for operation and maintenance would be on top of the estimated $4.5-billion capital outlay for new light icebreakers, a deepwater port and a support base, say the documents obtained by The Canadian Press under access-to-information laws.

A leading Arctic expert, Rob Huebert, said it's the first time the public has been given a clear glimpse at what kind of sustained financial commitment would be needed to meet the Conservative government's Northern strategy. He said the temptation would be for Canadians to recoil in shock and it's up to the federal government to lead the debate.

"You need to have this discussion," said Huebert, a professor at the University of Calgary's Centre for Strategic Studies.

The internal reports and memos trace the evolution of the Conservative strategy to assert Canada's presence in the North from the time the party was first elected in January 2006.

"From a cost perspective it cannot be over-emphasized that the vastness, isolation and lack of existing infrastructure will lead to increased costs in all aspects of implementation and operations in the Arctic," said the first assessment, penned by defence planners in 2006.

Subsequent documents have also underscored the financial "challenges faced in asserting Northern sovereignty initiatives." The federal government realizes the obstacles and the potential costs of operating in the North, said a spokesman for Defence Minister Peter MacKay.

"Minister MacKay recognizes that the Canadian Forces must be able to exercise control over and defend our sovereignty in the Arctic," Dan Dugas said in an email Thursday.

"He also wants to ensure that our military plays an increasingly vital role in demonstrating a visible Canadian presence and in helping agencies such as the coast guard respond to threats that may arise."

The Tories had initially proposed construction of three armed, heavy icebreakers to patrol the waters left open by receding ice packs. Experts predict the channels could be open to unimpeded summer navigation by 2015.

The ambitious $1.6-billion plan was abandoned in 2007 in favour of a $3.1-billion proposal to build as many as eight smaller icebreakers capable of operating off all three coasts. Although the current plan is more expensive, officials have defended it as better-suited for the navy.

The federal government has also proposed constructing a deepwater port and base in Nanisivik, Nunavut, and a winter warfare school of excellence.

The Defence Department cost estimates do not include what Ottawa would potentially spend on development and other non-military initiatives in the North.

The head of the army, Lt.-Gen. Andrew Leslie, conceded there will likely be a hefty price tag, but the cost of doing nothing would be more damaging.

"Think of it as a return on investment," he said in a recent interview with The Canadian Press. "It's sovereign Canadian territory; so it's part of our land.

"Who knows what untold mineral wealth might lay beneath those lands? Who knows what possible impact of folk using our North might be?"

The U.S. recently issued an Arctic policy paper which challenged Canada's attempts to establish control over the region. The 10-page paper, signed by former president George W. Bush just days before he left office, spells out Washington's intention to protect its security in the Arctic, regardless of Canadian or other international feelings.

The European Union has issued a similar report of its own.