Russia and the West are losing each other yet again. The magnetic attraction and repulsion between the two has been going on for centuries. Indeed, historians have counted as many as 25 such cycles since the reign of Tsar Ivan III.

In the past, however, Russia’s sharp anti-Western turns were reversed — usually out of simple necessity — after relations reached rock bottom. Not this time. On the contrary, the deterioration of the relationship nowadays has developed a momentum of its own.

There are four reasons for this. First, the “loss” of the Cold War, and with it imperial and superpower status, has created a deep and so far unresolved crisis in the collective mentality of Russia’s political class. Russian leaders continue to perceive the West as a phantom enemy in opposition to which all the traditional mythologies of Russian foreign policy are being resurrected.

Second, by the end of Vladimir Putin’s second presidential term, Russia’s modernizing dreams had been shattered. Modernization, indeed, simply turned out to be yet another redistribution of property to those on top, particularly those who came out of the St. Petersburg mayoral office and the Federal Security Bureau. The image of the West as an enemy has become the only ideological excuse for Mr. Putin’s model of the corporate state.

Third, the soaring price of oil has made the Kremlin’s inhabitants believe that they are all-powerful. Today’s Russia, which thinks of itself as a “great energy state,” laughs at its previous meager desire to catch up with little Portugal in terms of living standards.

Finally, a series of Western mistakes and misfortunes, a crisis in transatlantic relations, lack of leadership, and the growing threat of Islamic fundamentalism — in both the Middle East and Europe — have led Russian leaders to believe that the West is a sinking ship, to be abandoned as soon as possible.

While this belief unfortunately does have some validity, it requires one very important caveat: Russia is part of that ship. Russia can make advances to Hamas, Hezbollah, and Iran, and it can remind the Arab world that the Soviet Union helped it develop and offered it protection in the United Nations Security Council.

But in the eyes of Islamic extremists, Russia is part of the West — indeed, its most vulnerable part. Thus, it is Russia, with a soaring birth rate among its Muslim citizens that is the most attractive for expansion and take-over.

But Russia’s self-destructive confrontation with the West can be halted, and its centuries-old debate between Westernizers and the Slavophiles put to rest once and for all. This, however, will depend on Ukraine’s success on the path of European development it chose in the Orange Revolution of 2004-2005.

Ukraine does, indeed, present a threat, but not to Russia’s security, as Kremlin propagandists claim. The real threat is to the Putin model of a corporate, authoritarian state, unfriendly to the West. For the Kremlin’s occupants, it is a matter of life and death that countries that were once part of the Soviet Union but chose a different model of development — Ukraine being the chief example — should never become attractive to ordinary Russians.

The example posed by the Baltic nations does not threaten the Kremlin much, because they are perceived as foreign to the Russian psyche. Indeed, in Soviet films, Baltic actors were usually cast in the roles of Nazi generals and American spies. Ukrainians, on the other hand, are close to us in their culture and mentality. If they made a different choice, why can’t we do the same?

Ukraine’s success will mark the political death of Putinism, that squalid philosophy of “KGB Capitalists.” If Ukraine succeeds in its European choice, if it is able to make it work, it can settle the question that has bedeviled Russian culture for centuries — Russia or the West? So the best way to help Russia today is to support Ukraine’s claim that it belongs to Europe and its institutions. This will influence Russia’s political mentality more than anything else.

For if Russia’s anti-Western paranoia continues and the Kremlin’s Eurasian fantasy of allying with China lasts another 10-15 years, Russia will end up seeing China swallowing its Far East and Siberia. Indeed, the weakened Russia that will be Mr. Putin’s legacy will then also lose the Northern Caucasus and the Volga region to their growing Muslim populations.

The remaining Russian lands would then have no other choice but to attach themselves to Ukraine, which should by then have become a successful member of the European Union.

After 1,000 years, Russia will have come full circle, returning to Kievan Rus after wandering on the roads of the Mongol hordes, empire, communism, and farcical Putinism.

So Russia now has a choice: Ukrainian plan A or Ukrainian plan B.

Mr. Piontkovsky is a Russian political scientist and a visiting fellow at the Hudson Institute in Washington, D.C. © 2008 Project Syndicate.