Canadian Defense Minister Bill Graham staked his countrys claim on the Northwest Passage this week, setting up a showdown with the U.S. over control of the Arctic waters between the Atlantic and Pacific oceans. The U.S. government says the route is in international waters, which is largely a moot point since it is frozen solid. But Graham says that global warming could melt the Northwest Passage, turning it into a viable shipping lane and a valuable resource for Canada. Graham provoked another diplomatic squabble recently by reasserting Canadas rights to Hans Island, a barren Arctic rock also claimed by Denmark. We must exercise our sovereignty, Graham declared.