Russians are about to lose access to virtually all food imported from the West - which is to say, a significant portion of the food that Russians consume. President Vladimir Putin ordered the ban on imports to retaliate against Western countries that imposed economic sanctions against Russia after the downing of Malaysia Airlines Flight 17 over eastern Ukraine. More than anything that has happened this year - more than the annexation of Crimea, more than the latest crop of repressive laws passed by the parliament and more than the West's sanctions - the food ban marks a turning point for Russia. It is now fully and truly a country at war.

The ban on Western food has already led to price hikes and runs on supermarkets. Food prices were rising at a disturbingly high rate before the ban, and now they will probably skyrocket; there may also be shortages. Russians older than 30 have vivid recollections of such shortages, but the state propaganda machine is working hard to make people associate the looming hardships not with the memories of the failed Soviet economy but with the struggles of World War II. They are to think of their losses as heroic sacrifices made for the war effort. This propaganda, drawing on a wealth of cinematic and literary narratives of the glorious deprivations of wartime, may well prove successful with the vast majority of Russians who support the current war effort, at least in the short run.

A country at war invariably declares war not only on the outside enemy - in this case, the West, as represented by Ukraine - but also on the enemy within. In his landmark speech to parliament in March announcing the annexation of Crimea, Putin made reference to a "fifth column" of "national traitors" who are in cahoots with the West. With the ban on imported foods, he has broken an uneasy, long-standing truce with the group he views with the most suspicion: Russia's cafe society.

Putin's first decade at the helm coincided with a period of unprecedented prosperity in Russia, brought about by a boom in energy prices. This accidental fortune allowed Putin to solidify his power quickly and to institute authoritarian rule in Russia. As he was taking over the media and dismantling the electoral system, the country's educated and newly moneyed classes were discovering the pleasures of good food and wine. As it turned out, virtually anyone who had disposable income was willing to forfeit significant amounts of freedom if this coincided with gaining access to delicious meals in increasingly pleasing surroundings.

Truth be told, beautiful spaces came first and the food lagged behind by years. But, by about 2010, Moscow had a lot to offer even to discerning foodies. Last month, I spent about a week having the same conversation with different people over a series of good meals in different Moscow restaurants. We talked about the reversal of history, the country's exceedingly bleak prospects and emigration options. Invariably at some point in the conversation my interlocutors would look around and say something like, "But then there is this" - meaning a place that served good food from an inventive menu on an outdoor terrace.

My friends are right: The existence of these Moscow restaurants is inconceivable in the medieval warrior state into which Russia is turning itself. Putin knows this, too, and his food ban communicates a simple message to the differently minded: You no longer get to sit around in your cafes. The day after Putin announced the food ban, Prime Minister Dmitry Medvedev dealt a second, likely fatal blow to Russian cafe culture by announcing what amounts to a ban on WiFi access in public places.

In between lamenting the disappearance of Italian mozzarella, Australian rib-eye, Finnish yogurt and even cheap American drumsticks, Russian bloggers have also suggested in the past few days that by introducing what amounts to additional sanctions against his country, Putin may have weakened his government. The West's sanctions, of course, are increasingly designed in the hopes of effecting regime change rather than changing Putin's mind. Will either or both sets of sanctions work by stressing the elites enough to make them unite against Putin? If they do, we won't know it until it happens, so tightly closed is the system that Putin built. One thing is clear, though: Putin's Russia is becoming more truly itself, and the food ban is an important part of renouncing any pretense of being a part of the larger world.

Gessen is a Russian-American journalist and the author of "The Man Without a Face: The Unlikely Rise of Vladimir Putin."