But rather a matter of personal and national security, says Mark Bittman:

The notion of importing fruits and vegetables, the idea of having everything “fresh” all the time, was until recently inconceivable and is likely to become so again, as production and transportation costs rise and the absurdity of the “system” becomes evident even to those who now profit from it. When we ignore large-scale production of local food we invite apocalypse, or at least food shortages.

By creating a perverted norm, in which everything is always everywhere and little is seasonal, we have ceased to rely upon staples: long-keeping foods like grains, beans and root vegetables, foods that provide nutrition when summer greens, fruits and vegetables aren’t readily available. We expect a steady supply of “fresh” Peruvian asparagus, Canadian tomatoes, South African apples, Dutch peppers and Mexican broccoli. Those who believe they’re entitled to eat any food any time seem to think that predominantly local agriculture is an elitist plot to “force” a more limited diet upon us.

But there’s something far more important to fear: that when imports stop we won’t have the food to replace them, nor the farmers to grow that food.