A pair of Russian Akula nuclear submarines, like the one shown in this file photo, have been spotted off of Canada's East Coast. (Associated Press)

The Department of National Defence has sent a surveillance plane to waters off Canada's East Coast to monitor a pair of nuclear-powered Russian submarines in the area.

The attack subs were first spotted on Aug. 5 in international waters off Georgia, according to officials. The presence of the boats was leaked to the New York Times last week by anonymous security analysts.

While the subs were off the U.S. coast, the Pentagon was also monitoring their movements but no action was taken against the vessels.

Canadian officials said information indicates the Akula-class warships have now moved north.

'Commitment to sovereignty'

"For a variety of reasons, to demonstrate our commitment to sovereignty, we're watching to ensure we know what is happening along our coastlines," Defence Minister Peter Mackay told The Canadian Press. "Anything that comes near sovereign Canadian territory, we are going to react."

Defence Minister Peter MacKay says Russia has been "flexing its muscles" on the international stage. (Canadian Press)Akula-class subs are equipped with surface-loaded cruise missiles and surface-to-air missiles but are not believed to pose any kind of threat, defence officials said.

A long-range CP-140 Aurora plane will keep an eye on the subs, which have remained outside Canada's 12-nautical-mile territorial limit, according to Canada Command, the Ottawa-based military headquarters in charge of continental defence.

It's unclear whether Canada took the initiative to have a patrol plane watch the vessels or whether the U.S. Northern Command requested that the submarines be tracked.

Canada Command spokesman Lt. Noel Paine declined to disclose the details of the surveillance mission, calling it a "routine" patrol.

Russian posturing

The arrival of the Russian subs off the North American seaboard is the first documented time in more than a decade the country has operated vessels in the region, according to military historians.

Col. Gen. Anatoly Nogovitsyn, deputy chief of the Russian military, has shrugged off foreign concerns about Russian sub patrols near North America. (Sergei Karpukhin/Reuters)During the Cold War, the United States and the Soviet Union regularly patrolled each other's coastlines in an effort to collect military information and to track each other's fleet movements.

Analysts have suggested the arrival of the subs is part of Russian posturing.

Deputy chief of staff for the Russian armed forces, Col. Gen. Anatoly Nogovistsyn, said the unannounced sub movements are "part of a normal process" and are travelling within recognized international regulations. There is no need for "hysteria" about their presence, Nogovistsyn told Reuters.

The patrol is just a matter of the country's fleet not sitting idle or continuing to travel around in circles on Russia's internal routes, he said: "The navy should not stay idle at its moorings."

Fight for the Arctic

MacKay said the submarines have not done anything considered threatening. But the minister added there is a pattern of "Russia flexing its muscle" over recent months.

The Arctic, with its prospective mineral wealth and ill-defined borders, has become an area of intense competition among Canada, Russia, the United States, Denmark and other countries.

The Russian navy fired two long-range underwater missiles in Arctic waters near the North Pole in July. Russia has also launched several bomber flights that have brushed up against Canada's Arctic border.

In February, Canadian fighter jets scrambled to intercept a Russian bomber less than 24 hours before U.S. President Barack Obama was to visit Ottawa.

The Russian Embassy in Ottawa has denied that the presence of the latest vessels has anything to do with staking claim in the Arctic.

The Canadian navy is preparing to conduct an anti-submarine exercise in the Arctic later this month.

With files from The Canadian Press and The Associated Press