The Ukrainian crisis has become a real-life war game that is being played out to an unknown conclusion with gripping suspense. The downing of a Malaysian Air jetliner with 198 people aboard demonstrates the extent to which the game, initiated by Russian president Vladimir Putin, has had horrific consequences.

Mr. Putin approached the game from the outset as part of his project to rebuild Russia's sphere of influence in its former vassal states. At first, his objective was simply to block the ambitions of many Ukrainians to become part of the European Union. More recently he grabbed Crimea from Ukraine and then gave aid to pro-Russian separatists in eastern Ukraine, where his endgame remains yet unclear. Will he again seize Ukrainian territory? Or does he simply want to weaken and divide Ukraine in pursuit of forcing terms upon that country?

Mr. Putin's latest move suggests he has added a new objective - weakening the European Union. His ban on importing a range of foods will fall most heavily on some of the newer European Union members that were part of the Soviet bloc 25 years ago. They will lose significant markets for vegetables, fruits, butter and other foods on Mr. Putin's list. In addition, Ukraine will undoubtedly ask European markets to also absorb farm goods formerly shipped to Russia.

European agricultural policy will be forced to adapt to these market changes, probably at the cost of much higher government spending for farm subsidies.

While many see the Russian food ban as a self-defeating reaction to U.S. and European economic sanctions on Russia, it is likely to impose difficult political and economic costs on the European Union. The effect on the United States, on the other hand, should be comparatively trivial. And contrary to initial reports, the effect on Russian consumers is also likely to be small. Other suppliers can fill most of their needs.

The sanctions do not necessarily mean that Russia is retreating into its shell. It will continue, at least for now, to import large quantities of grain from the United States and elsewhere. But they do signal that Mr. Putin thinks he can move further away from dependence on foreign supplies if the confrontation over Ukraine remains unresolved. That is another signal to Europe that its own dependence on Russian energy supplies is at risk if it continues to push for stronger ties with Ukraine.

Like the carefully targeted sanctions applied by Europe and the United States to Russia that are intended to persuade Mr. Putin to negotiate a peaceful resolution of the Ukraine crisis, Mr. Putin's countermoves are intended to apply Russian pressure on the EU, with the implication that more painful actions might be next.

Like the recent Russia military maneuvers on Ukraine's border, they are a signal that Mr. Putin, so far, does not intend to be the first one to blink in this conflict.

As an autocrat, he doesn't have to answer to his constituents as do the leaders of the democracies that make up the European Union. The EU must be willing to hold the line against Mr. Putin's expansionist ambitions.