Canada is not the first nation to deal with underwater prowlers. Earlier this year, a Chinese nuclear submarine penetrated Japanese waters. It was tracked, and the Chinese later apologized for the incident. During the Cold War, Sweden had numerous violations of its waters by submarines, the most famous violation being the 1981 incident in which a Soviet Whiskey-class submarine ran aground in Swedish waters (the Whiskey on the rocks incident).
The question, of course, is who would be prowling around Canada. Nobody is going to come forth and admit their submarines are deliberately violating another countrys territorial waters, even when there is extremely clear evidence as to the fact the waters are being violated (like a submarine caught on the rocks ten meters from shore). The Canadian Arctic is one of the hardest places to operate in mostly because there is very little in the way of logistic support that far north. It was not even really accessible until the advent of nuclear-powered submarines. Such boats are the prime suspects for these incursions.
The nuclear-powered submarine first proved its ability to carry out Arctic Operations when the USS Nautilus transited the North Pole in 1958. Since then, nuclear submarines, particularly those of the United States, have owned the Arctic (with the Russians and Royal Navy also operating there). Which country they belong to will not be easily ascertained. The United States would move to the head of the list due to proximity (being next door to Canada) and the largest number of nuclear submarine force in the world (55 attack submarines and 14 ballistic missile submarines). American submarines would find the Canadian Arctic to be a good shortcut (a few thousand kilometers) from the bases at Groton and Norfolk in the Atlantic to Pacific bases like Pearl Harbor, Guam, and San Diego. Russia, though, has a considerable force of nuclear submarines (15 nuclear attack submarines, 6 cruise missile submarines, and twelve SSBNs), and the track record of incursions into other countries waters, as Sweden can readily attest. The Royal Navy has twelve SSNs (five Swiftsure-class and seven Trafalgar-class) and four SSBNs (four Vanguard-class vessels), and a Royal Navy sub would be going out of its way to reach the Canadian arctic. Barring an accident, the identity (or identities) of Canadas underwater prowlers will remain a mystery for years as is typical for the silent service. Harold C. Hutchison (firstname.lastname@example.org)
Since 1999, Canada has detected an average of two incursions, by unknown submarines, a month in its Arctic waters. This is not the first time that Canada has had this sort of problem. There is a long-running dispute with Denmark over which country owns Hans Island, a three-square kilometer island off the coast of Greenland. That dispute heated up recently when Denmark sent a frigate to reinforce its claim. That led to Operation Narwhal, a major exercise designed to show Canadas ability and, more importantly, its will to protect its Arctic territory.