The United States government has a dangerous penchant for military intervention, so after Vladimir Putin invaded Crimea, it was a relief that no one talked about sending troops or deploying bombers. Sen. John McCain scotched any such notion by acknowledging glumly that "there is not a military option."
Silly him. For the most bellicose hawks, there is always a military option. After a brief lull, some of the people who beat the drums for war in Iraq -- and have done likewise for Iran -- now propose that we put American lives at risk on behalf of Ukraine.
This comes as a bit of a surprise because we have never made a commitment to fight for Ukraine. We have made such commitments to the 27 other countries that belong to NATO. The alliance charter obligates every member to treat an attack on one as an attack on all.
But Ukraine has not been included in the club, and judging from polls, Ukrainians actually didn't want to be included. To some commentators, it doesn't matter: We should use our military might to protect Ukraine anyway.
Leslie Gelb, president emeritus of the Council on Foreign Relations and a veteran of Jimmy Carter's administration, urges President Barack Obama to send F-22 fighters to Poland and make it clear he will use them if Putin advances farther into Ukraine.
Thomas Donnelly, a defense analyst at the conservative American Enterprise Institute, views the failure of American politicians to endorse "boots on the ground" in Ukraine as "a crippling weakness." Writing in The Weekly Standard, he says, "Preserving the peace on the Eurasian landmass demands land forces."
Fox News' Charles Krauthammer, who exhibited calm indifference to the Russian invasion of Georgia under President George W. Bush, now wants NATO to dispatch military trainers and advisers. He favors a "tripwire" strategy that would "establish a ring of protection at least around the core of western Ukraine."
This notion brings to mind the response when a French defense official was asked the smallest British force that would be of use to France in case of war with Germany. The answer: "One single private soldier -- and we would take good care that he was killed."
What these proposals have in common is that they would interpose our soldiers as hostages, virtually forcing the U.S. to go to war should Putin advance. The assumption of the advocates is that by shackling ourselves to Ukraine, we will stop him in his tracks. The risks of fighting NATO, they argue, deterred the Soviet Union and would undoubtedly deter Putin.
But how can they be so sure? These critics accuse Obama of inviting aggression by failing to make good on his threats regarding Syria.
Yet they somehow assume Putin would take this sort of gesture by the president as an unbreakable commitment.
What they omit is what happens if they are wrong. In that case, Americans would find ourselves fighting a war against Russia over a place that matters a great deal to Russia's security and none at all to ours. That, or Obama would have to slink away and admit he was bluffing, inviting doubts about every other U.S. defense commitment.
Contrary to myth, our 1994 deal getting Ukraine to surrender its nuclear weapons doesn't obligate us to use force to protect it. In case of trouble, the agreement promises nothing but consultations.
The idea that a few advisers or planes would check the Russians is based on hope, not history. During the Cold War, the U.S. deterred Moscow by drawing bright red lines and backing them up with massive forces and willing allies.
It also relied on our nuclear weapons in Europe. The ultimate guarantee against invasion was the possibility that we would turn Russia into a charred wasteland of radioactive debris. That threat is far less credible than it was then.
Committing ourselves to the defense of Ukraine is risky enough by itself. But it also means putting our fate in the hands of Ukrainian politicians who have longstanding grudges against Russia and may be emboldened by our presence. Once we put forces in Ukraine, we have no assurance our allies will act in our interest.
Sending NATO forces to Ukraine is like walking into a biker bar with an acquaintance who has a real grudge against bikers. Maybe things will go fine, and maybe not. If not, we'll wonder why we didn't stay out when we had the chance.
(Steve Chapman is a columnist of The Chicago Tribune and Creators Syndicate.)