Canadian Prime Minister-designate Stephen Harper has defended plans to send military ice-breakers to the Arctic in defiance of US criticism.
Mr Harper criticised opponents for anti-US positions during the election
US ambassador David Wilkins said on Wednesday that Washington opposed the plan and, like most other countries, did not recognise Canada's claims.
Mr Harper said his mandate was from the Canadian people, not Mr Wilkins.
Mr Harper's Conservatives have promised to defend Canada's northern waters from claims by the US, Russia and Denmark.
The party won a narrow victory over the outgoing Liberal administration in Monday's election, but failed to secure an overall majority.
The Conservative plans include the construction and deployment of three new armed heavy ice-breaking ships and an underground network of listening posts.
The BBC's Lee Carter in Toronto says Canada has only recently woken up to the fact that, with global warming being blamed for melting ice in the Arctic, the so-far-mythical northwest passage, which could link the Atlantic and the Pacific, may in fact become a reality.
The US and Canada, together with Denmark, Norway and Russia, have competing claims on parts of the Arctic and the economic bounty they may yield, including trade routes, fishing rights, and oil and gas.
The US has challenged Canada's current claims, saying that it considers much of the region to be international waters.
Ambassador Wilkins described the Canadian position as creating a problem that did not exist, prompting an angry reaction from Mr Harper.
"The United States defends its sovereignty, the Canadian government will defend our sovereignty," he said.
"It is the Canadian people we get our mandate from, not the ambassador of the United States."
Mr Harper had criticised election opponents for attacking the US in a bid to win votes.