Toronto ? A dramatic deep-sea submarine dive to plant the Russian flag under the North Pole last week has rattled Canadian politics and underscored the growing stakes as the ice cap melts in the oil-rich Arctic.

Canada and the United States scoffed at the legal significance of the dive by a Russian mini-sub to set the flag on the seabed Thursday. “This isn’t the 15th century. You can’t go around the world and just plant flags” to claim territory, Canada’s minister of foreign affairs, Peter MacKay, told reporters.

But the government here has been thrown on the defensive by the Russian action, accused by critics of doing too little to meet a deadline for the five Arctic nations to map and claim huge areas of the Arctic seabed.

A U.S. Coast Guard icebreaker left Seattle on Monday for an area 500 miles north of Barrow, Alaska, where a contingent of 20 scientists are to continue compiling an undersea map in preparation for a U.S. claim of the resources there.

Canada has not equipped itself to do the same. It has no icebreakers heavy enough to tackle the Arctic ice head-on.