THE UPHEAVAL IN the international order prompts Canadians to think thoughts that would have seemed preposterous a short time ago. We hear our Department of National Defence is “modelling” what a US invasion might look like. A former Canadian chief of defence staff says we should keep our “options open” with respect to building our own nuclear deterrent one day.

Anyone who had been asleep for a few years and suddenly woke up would think the world had gone mad. They would be right.

One of the key developments of the last year is the loss of confidence that the United States will honour its Article V commitment under the NATO Treaty, particularly in the light of a Russia that is seen to pose a greater threat than at any time since the end of the Cold War. Article V is the promise to come to the aid of any ally under attack. A strike against one member, in other words, would automatically widen into a war with the entire alliance. If adversaries believe that promise is now conditional, negotiable, or politically fragile, then the deterrent logic collapses. Indeed, there is now a fear—apparently put aside for the moment as far as Greenland is concerned—that the US might itself attack (or at least coerce) its allies.

This raises monumental questions for the rest of NATO. One of these is whether the US nuclear guarantee, the ultimate expression of its willingness to fulfill Article V, is still worth anything. In a major study prepared for the Munich Security Conference, European security experts explored possible responses, including the creation of an independent deterrent for the continent.