Ever since Vladimir Putin first became Russian president in 2000, EU leaders have been unable to establish a long-term strategy toward their powerful Eastern neighbor.

The EU looked on as Putin invaded Chechnya just weeks after he entered the Kremlin. That part of southern Russia is now so combustible that if it does explode, no military force will be able to bring stability or peace to the region. It’s a cauldron waiting to boil over, and when that happens, it will have terrible consequences for the Caucasus and for Russia’s internal security.

When Putin seized the territories of Abkhazia and South Ossetia from Georgia in a short war in 2008, European leaders again wrung their hands. Since then, Russia has established the facts on the ground. Georgia’s territorial integrity has been destroyed.

Moldova’s territorial integrity has been affected too. There, for over two decades, Russian-backed leaders in the breakaway region of Transnistria have done everything possible to undermine Moldova’s fragile democracy and its ambitions to move closer to the EU.

And now Crimea. Since February 28, this peninsula in southern Ukraine is under the de facto control of Russia. No matter how U.S. or EU leaders react, Putin will push to consolidate Russia’s grip on this strategic part of Ukraine. It is as if Putin is trying to reverse the collapse of the Soviet Union, an event that Putin described as one of the worst tragedies ever to hit Russia.

It is time for European leaders to recognize that the age of illusions about Russia is over.

One of those illusions was built on the premise and hope that Putin would modernize his country. That is something that several European governments have longed for—especially Germany, but also Russia’s other Western neighbors, not least Poland.

For decades, successive German governments have reached out to Russia, believing that the modernization of the Russian economy would eventually lead to the creation of a modern political order where the rule of law would prevail. Yet Germany’s Ostpolitik, or Eastern policy, has failed, as Putin’s policies in Chechnya, Georgia, and now Crimea have shown. Surely, any believer in Ostpolitik must now admit that a major illusion has been shattered.

Europe’s other illusion was that Russia would accept the reunification of the continent. In fact, Putin has actively sought to prevent Europe from being reunited.

Russia has found it very difficult to accept that Poland, the Baltic states, and other former Soviet satellites have joined the EU and NATO. Repeatedly, Moscow has tried to undermine these countries’ self-confidence by imposing trade embargoes or by exploiting their energy dependence on Russia.

But Putin’s indiscriminate use of energy resources to retain the Kremlin’s influence over this part of Europe—especially his belief that Russia could charge prohibitive prices for the gas it supplies to the Baltic states—has backfired. Russian energy giant Gazprom, which used to be one of Moscow’s most powerful and effective foreign policy tools for cajoling its Western neighbors, is now in the midst of a major dispute with the European Commission over alleged abuse of power.

The EU and Russia are now engaged in a massive and dangerous struggle for Eastern Europe. Any illusions that Putin might allow the countries in the shared neighborhood to move peacefully toward the West have been crushed—thanks to Russia’s policies in Georgia, Moldova, Ukraine (both before and since the 2004–2005 Orange Revolution), and elsewhere. Through those policies, Putin has tried to build a new Iron Curtain across the continent.

In the short term, Putin may believe he can achieve that, while convincing his people with his powerful and insidious propaganda and control of the media that he is simply protecting ethnic Russians living outside Russia. He can also establish facts on the ground in a way that neither EU nor U.S. leaders can counter with sanctions, boycotts, or other measures.

But sooner or later, even Putin’s own citizens will begin to question what Russia stands for under its current president.