Zbigniew Brzezinski. TK

What would Zbig do?

Former national security adviser Zbigniew Brzezinski, that is, and the question is what to do now in the Ukraine crisis.

Few are better equipped to answer that question than is Mr. Brzezinski. Son of a Polish diplomat, he has spent a lifetime thinking about the geopolitics of Eastern Europe, from posts in government, academia and, currently, at the Center for Strategic and International Studies.

As those who know him would expect, Mr. Brzezinski has a plan: The Obama administration and its allies should help Ukraine become a truly independent state in the center of Europe. Here are excerpts of a conversation in which he describes how to go about that:

The stakes in Ukraine: "What is at stake is a secure and open Europe," Mr. Brzezinski says. The alternative is "some sort of a Russian imperial enterprise next door based largely on force, and as a result probably quite unstable. So the stakes are really enormous."

The approach the West should take now: The effort at this point, says Mr. Brzezinski, should be simultaneously two-fold: The first objective should be to see whether an accommodation with Russia is still possible, which he believes it could be. The second objective should be to ensure that the Russians, and particularly President Vladimir Putin, understand the consequences of not reaching an understanding with the international community.

What goal to pursue: The West should seek "an understanding that Ukraine is free to pursue its objective to become more European." Under this understanding, Ukraine wouldn't become a member of the North Atlantic Treaty Organization, and full membership in the European Union would still be "some distance away," as it has been for Turkey for years.

At the same time, though, Ukraine wouldn't become a member of the Eurasian Union that Mr. Putin is trying to create around Russia's borders. Instead, Ukraine would have an independent status much like the one Finland enjoys now: "Like Finland, it would have normal commercial relations with Russia while becoming an increasingly modern European democracy."

To reach this goal, "we would probably have to put aside the resolution of the Crimean situation for the moment," and over the longer run help Ukraine seek to reach "a condominium on Crimea"—some kind of joint control or ownership or oversight.

How to pressure Russia to accept this outcome: This "will only be appealing to the Russians if they realize that their use of force carries the risk of confrontation. Here I think it is important for the Ukrainians to recognize that they have to be willing to fight for what they want. And we have to be willing to make it clear that they will not be alone."

That means offering Ukraine weaponry—defensive in nature, but suitable for urban warfare. "I would be willing to promise it to them now," Mr. Brzezinski says, and then provide the weaponry depending on the circumstances that unfold. Among other things Ukrainians need, Mr. Brzezinski says, is help from the West to "re-create their army" and to be able to engage in protracted urban resistance.

The usefulness of economic sanctions: "On sanctions, I think [President Barack] Obama has played it prudently," Mr. Brzezinski says. Mr. Putin's Russian friends already have felt real pain; even the Russian president has acknowledged that sanctions brought some of his allies to "tears." More broadly, Mr. Brzezinski says: "The Russian economy now is in no shape for expanding sanctions. I think there are strong elements at the top of Russian society that understand this risk. It could be a catastrophe for Putin. So the scope of sanctions should keep escalating."

Other sources of pressure on Russia: "I don't think it is going to be easy. But the Russians have to ask themselves, even if Putin won't, what are the consequences of a nation of 45 million people turning hostile."

Already, Mr. Brzezinski says, Mr. Putin has to be concerned about the seeds he has sown next door: "He has created widespread animus toward Russia in Ukraine. And Ukraine has never historically been anti-Russian."

And it could get worse. Mr. Brzezinski notes that Mr. Putin needs to be concerned about the ability of outside forces to stir up trouble for him among Russia's own large ethnic minorities, particularly its Muslim minorities.

How to best explore chances for an understanding with Russia: Mr. Brzezinski suggests further discussions between Secretary of State John Kerry and Russian Foreign Minister Sergey Lavrov, perhaps escalating to quiet conversations between Vice President Biden and Russian Prime Minister—and former President— Dmitry Medvedev if the dialogue progresses. And he suggests that Mr. Obama address the nation on the issues at stake.

Write to Gerald F. Seib at jerry.seib@wsj.com