The Arctic ice on North America’s northern border is melting. Within a decade or two, for at least parts of the year, foreign ships — private and military alike, friendly and hostile — will be able to pass through the Northwest Passage and Arctic waters at large. Economies in travel time from Europe to Asia (and the reverse) will prove irresistible, as will the vast resource deposits of the Arctic seabed, still awaiting recovery. This will, over time, assuredly introduce a new strategic consciousness into the decision-making of North America’s political class; a consciousness — and, before long, a new strategic culture — enabled by a popular paranoia about foreign interests promiscuously penetrating the continent’s heretofore near-perfect territorial sovereignty.

The United States is in relative strategic decline. It will uncontroversially remain the preeminent strategic power until about the halfway point of this century, but the increasing relative strength of China and other combinations of important states poses both psychic and practical consequences for North America. Psychically, diminished American strategic weight and prestige — coupled with a newly porous Arctic border and an understanding of the onshore devastation that could be wrought by enemies enabled by new-century technology — will heighten the sense of vulnerability of the U.S. and Canada, and also radically alter the risk-reward preferences and calculations of both countries. For Canada, diminished American power and increased American vulnerability to attack should destabilize the long-held, implicit strategic assumption that America will necessarily defend the northern part of the continent should we come under attack.