There’s a lively debate going on over how far we ought to resist Vladimir Putin’s aggression in Ukraine. Of course, all our sympathies are with Ukraine, a nation which in the 20^th century suffered a genocide at the hands of a Russian government: between 6 and 12 million died in the artificial terror famine engineered by Josef Stalin. (Watch the neglected masterpiece Famine 33 — Ukraine’s answer to Schindler’s List, for a glimpse into earthly hell.) For that reason alone, Ukraine’s safety has the same moral import as that of Israel. Decent people are glad that Israel has a nuclear deterrent, and it was criminal folly when the West conned the newly-free Ukrainians to give up their legacy nuclear weapons, with promises that we would protect their independence from the Russians by force if necessary.

There are important differences between the Israeli and Ukrainian stories. While no Nazi government survived 1945, the Jews in newborn Israel were surrounded by Arab states with a similar exterminationist agenda; indeed, important Arab leaders had actually cooperated in the Holocaust, convincing operatives such as Eichmann to kill Jews rather than deport them to Palestine. The Russian government today wants to subdue, corrupt, and exploit Ukraine — not impose another Holodomor, or drive the Ukrainians “into the sea.” If Putin and his kleptocrats were in fact contemplating for Ukrainians anything like the extermination that Islamists envision for Israel’s Jews, then there would be no debate: Americans would extend our nuclear umbrella to cover that nation, whatever the risks. Thank God, no such murderous project is remotely plausible.

Ukraine is not today a nation in danger of mass extermination. It is a weak, impoverished country that would like to join the West and hitch its fortunes to the EU, NATO and the Euro. As John Mearsheimer wisely points out, Russia is a Great Power that refuses to see its neighbor ally with its rivals. The U.S. was likewise appalled when Imperial Germany, in 1917, tried to win Mexico as its ally in case of war. In fact, the clumsy Zimmerman Telegram did more than the sinking of U.S. ships to rally public opinion behind Woodrow Wilson’s messianic drive to war. Why should we expect Russians to feel any less embattled when Great Power rivals recruit their nearest and largest neighbor? Would we tolerate a Chinese-allied regime in Canada? Not for a second.

President Obama knows these facts of history, which even might filter in to the fevered minds of promiscuous interventionists like Senator John McCain. We will not march ahead to fight a war against a nuclear-armed Russia to defend the sovereignty of Ukraine, any more than we will plan to fight China to save Taiwan. We would not choose these wars, and the American people would not support them. But we could well slip into such wars, in much the same haphazard manner that European powers blundered into war in 1914 — by sending mixed signals, offering promises that were intended to be empty, and posturing and blundering until a ruinous war seems like the only “honorable” alternative.

In Churchill, Hitler, and the Unnecessary War, Patrick Buchanan reminds us of Neville Chamberlain’s reckless, insincere promise to defend Poland against a German invasion — a line drawn in the sand two years too late — which the poor, doomed Poles took at face value, leading to a war in which one out of four Poles (Jewish or Gentile) would die, which would end with Poland  occupied by a totalitarian power for almost 50 years.

Tom Rogan, in National Review, warns against making Ukraine a comparable promise, in order to bluff Putin’s Russia into letting Ukraine join the Western economy and Western alliances. In fact, the current policy of bluster-and-cower pursued by Obama relies for its slim chance of success on just one factor: We are hoping that Putin realizes how easily we could blunder into a shooting war, where nuclear weapons would indeed be on the table.

Let’s unpack this honestly: We are warning the Russians that while there is no public support for a war on behalf of Ukraine, which is not one of the U.S.’s vital interests (though it’s one of Russia’s), we will pursue risky policies that encourage the Ukrainians to resist Russian aggression, aware that our actions might drag the U.S., willy-nilly, into a potential nuclear war. In other words, we’re playing chicken with millions of lives, driving a borrowed car, in order to claim a road in someone else’s neck of the woods.

Such a war would not meet the Christian criteria to qualify as just: While the cause of Ukrainian sovereignty is a good one, its likelihood of success is extremely uncertain, and the risk of civilian deaths is massively disproportionate to the evil we’d be trying to fix — the unjust extension of Russian power over a former Russian province. So a war against Russia for Ukraine would be not just stupid but sinful. Let us pray that our leaders reflect with grave attention on the lessons of 1914, and find a rational compromise short of reckless confrontation and mass destruction.