He's getting predictable. Photographer: Alexey Druzhinin/AFP/Getty Images
He's getting predictable. Photographer: Alexey Druzhinin/AFP/Getty Images

Events in Ukraine are following a familiar pattern. When evidence mounts of Russian military activity on the eastern border of Ukraine, Western leaders re-up their threat of economic sanctions, and President Vladimir Putin makes conciliatory gestures in response.

On this occasion, Putin asked the Russian parliament to rescind a March 1 law that gave him legal authority to invade Ukraine, saying he supported a cease-fire. Very considerate of him. And shrewd: It will almost certainly be enough to ensure that European Union leaders don't move to impose economic sanctions on Russia at their meeting this week.

Standoff in Ukraine

Yet there is little doubt about Russia's intentions or actions. The North Atlantic Treaty Organization says Russia continues to antagonize Ukraine, and Russian hardware appears to be moving to the border uninterrupted. The rebels responded to the cease-fire on Tuesday by shooting down a Ukrainian helicopter with a surface-to-air missile they didn't get from an army surplus store, killing nine servicemen. And as U.S. Secretary of State John Kerry said on Wednesday, Putin's sacrifice of the legal authority to invade "could be reversed in 10 minutes, and everyone knows that."

Putin's gestures have put President Barack Obama in the invidious position of having to decide whether to go it alone with sanctions that would target Russia's energy and financial sectors, as well as ban technology transfers. U.S. companies, unsurprisingly, are loudly pressing the administration not to act, fearing they will lose business to their European competitors. If Obama backs off, Putin can continue destabilizing Ukraine undisturbed; if the administration does impose sanctions, the U.S. and Europe will be split -- also a gain for Putin.

What to do? There is a way to escape this continuous loop: Both Europe and the U.S. should be much more specific about what Russia must do to avoid sanctions. So far, the U.S. and allies such as the U.K. have called for Russia to stop supplying the Ukrainian rebels with arms.

Such generalities allow the game to continue. The U.S. and the EU should instead jointly tie sanctions to Putin's agreement to have personnel from the Organization for Security and Cooperation in Europe seal off Russia's border with Ukraine's two separatist provinces, Lugansk and Donetsk.

From the moment Ukrainian President Petro Poroshenko proposed a unilateral cease-fire to end the crisis, combined with measures to devolve more power to Ukraine's regions and protect Russian-language rights, he said the deal was contingent on sealing the border. Poroshenko has been pushing the OSCE idea, and it should become the centerpiece for Western pressure.

In May, German Chancellor Angela Merkel and Obama declared that unless Ukraine's presidential election was allowed to proceed, they would impose economic sanctions. Putin appeared to respond. Now they should jointly make a new demand: acceptance of European border guards.

These monitors would obstruct the flow of Russian tanks, missiles, guns and "volunteers" into Ukraine. If Putin accepts the proposal, then the crisis will recede. If he is reluctant, then his true intentions will be all the more clear -- and any symbolic conciliatory gestures will be exposed for what they are.

To contact the senior editor responsible for Bloomberg View's editorials: David Shipley at davidshipley@bloomberg.net.