The question is posed by my old friend Eric Edelman on The Weekly Standard website. Eric and I overlapped at Cornell and later in graduate school at Yale. After getting a Ph.D. in diplomatic history with a dissertation on Turkey’s entrance into NATO, he joined the Foreign Service. In time, he served as ambassador to Turkey (a job I crave myself), and he was last visible as Undersecretary of Defense for Policy, a post he held from 2005 to 2009.

Here is the answer he gives:

First, [the Ukraine] matters because—despite Putin’s risible claims of anti-Russian violence in Crimea and eastern Ukraine (even Angela Merkel reportedly told President Obama that she thinks Putin is “in another world”)—this is military aggression against a neighboring independent state in the heart of Europe that violates the U.N. Charter and the Helsinki Final Act. Moreover, the pretext upon which it is based, protection of Russian national minorities in Ukraine, could also be used against NATO member states like Estonia, Latvia, and Lithuania, and under Article 5 of the NATO treaty, “an armed attack against one [member state] .  .  . shall be considered an attack against them all.” The future viability of the alliance is at stake here.

Second, if Putin can pull off a smash and grab operation against Crimea without being made to pay a serious and significant price, others will draw their own conclusions. Would the “international community” exact a price subsequently if China seized the Senkaku Islands or even Taiwan? Would Pyongyang or Tehran conclude that it might have more leeway for aggressive moves against its neighbors?

Third, there is a huge nonproliferation issue (allegedly the president’s highest national security priority) at stake. Ukraine, as one of the successor states to the former Soviet Union, found itself in 1991 with nuclear weapons on its territory to which it laid claim. It was one of the Clinton administration’s signal diplomatic achievements to have gotten Ukraine, Belarus, and Kazakhstan to agree to return the nuclear weapons on their respective territory to Russia, leaving one nuclear weapons state on the territory of the former USSR rather than four. In return, the United States, United Kingdom, and Russia all signed, along with Ukraine, the Budapest Memorandum, which accompanied Ukraine’s adherence to the Nuclear Nonproliferation Treaty. Inter alia, that document committed Russia to “respect the independence and sovereignty and the existing borders of Ukraine” and imposed on Russia an “obligation to refrain from the threat or use of force against the territorial integrity or political independence of Ukraine, and that none of their weapons will ever be used against Ukraine except in self-defense or otherwise in accordance with the Charter of the United Nations.” If left standing, Russian aggression will establish that security assurances offered by the nuclear weapons states to states that willingly give up their nuclear weapons or weapons programs mean precisely nothing.

Eric also has some things to say about what can be done to bring Vladimir Putin to heel, and they deserve heeding — especially because he knows whereof he speaks when he talks about military matters in particular.

I would merely add that it would not take much effort on our part to bring down the Russian economy. The place is a banana republic, or — to be more precise — a petrodollar paradise. Call the Russian bluff. Batten down the hatches and bring oil and gas to Europe from other sources this Spring, and the ruble will crash and Russia fall apart. Seventy-five percent of its exports have to do with energy.

Polls show that seventy percent of the citizens of Russia oppose Putin’s intervention in the Crimea now. If the Russians do not export their oil and gas, they will have next to nothing to eat — and that will not sit well with the Russian people.

Moreover, the place is a kleptocracy: run by and for a handful of oligarchs who profit from exploiting for their own benefit the resources that rightly belong to their fellow citizens, and they stash their loot abroad. Freeze all assets owned abroad by Russian nationals, and his fellow oligarchs will be calling for Putin’s scalp.

Let me add that Putin himself has billions and billions stashed abroad. I am told by a Russian expert here at Stanford that he may be the world’s wealthiest man, and we know under whose name his stolen riches are hidden. Remember: we read their mail.

The coup that Putin is trying to pull off is predicated on the presumption that we and our allies in Europe are so weak-kneed that we will acquiesce. There is one thing that you can be certain of. If we do acquiesce, this will not be Vladimir Putin’s “last territorial demand in Europe.”

There is this to be said in defense of Neville Chamberlain. Hitler made such a promise at the time he signed the Munich Agreement, and Chamberlain believed it. Putin has said nothing of the kind.

To acquiesce is to risk losing everything that we gained in World War II and the Cold War. Ron Paul, Rand Paul (I suspect),  and the Cato Institute notwithstanding, our long-term well-being depends upon there being a tolerably reliable international order relatively free from thuggery and open to trade. This does not mean that we have to be deeply concerned with every bit of foolishness that goes on. It does not mean that we have to be the world’s policeman. But when a power possessing nuclear arms runs amok and begins seizing territory from its neighbors, we have to act.

Isolationism made sense in the 19th century when we could rely on the British to support such an order. It made no sense in the 1920s and the 1930s as we learned the hard way in 1941, and it makes no sense now.

I am not suggesting that there is any need for histrionics. Nor do I think that we need to put boots on the ground. We simply need to use the economic levers at our disposal. In situations like this one, the less that statesmen posture the better. Talk softly, and wield a big stick with vigor and cunning. That should be our policy.