Burlington Vermont is cold in late November. Huge mounds of recently cleared snow attest to the coming of winter, which in this part of the world, just below the Canadian border and far from the warming influence of the oceans, is long, dark and absolutely freezing.

The shops of Church Street are doing a brisk business in quilted jackets, boots and woolly hats. With its open log fires, law-abiding citizens and reusable coffee mugs, there’s a touch of a little Denmark in North America about this place. That is until you see the row upon row of F-16 fighter jets in the airport terminal.