There has been much talk of historical analogies since Russia invaded Ukraine. Are we living through another Cuban missile crisis? Is it October 1973, when another endangered American ally—Israel—faced destruction and desperately needed arms, with the danger of Russian retaliation if escalation went too far? Or are we in 1939, on the brink of cataclysmic world war?

While history never repeats itself exactly, we should never rule out the worst-case scenario, precisely so that that we can avoid it. So it is worth revisiting the casus belli of 1939. Like Ukraine today, Poland then was a proud but overmatched buffer state with few natural barriers to stave off invasion by a more powerful neighbor from multiple directions, depending for its security on a precarious guarantee issued by distant powers in the West.

The usual story is that, after Hitler violated his pledges at Munich by moving into rump Czechoslovakia in March 1939, British opinion soured on Chamberlain’s appeasement policy, and Chamberlain woke up to the threat posed by Hitler, too late to secure the best outcome as a more forthright response to Hitler at Munich might have allowed – but still in time to resist German aggression and save the world from Nazi subjugation.

While there is truth in this, there is a more painful interpretation as well. Chamberlain, like many statesmen reacting to bad news, veered from one irrational extreme to the other in 1939, from abject appeasement of Hitler to mindless confrontation. Poland was his ostensible object of concern, but he did not really favor her cause. Chamberlain’s notorious guarantee of Poland’s “independence,” but not territorial “integrity,” reflected his ambivalence, as Poland had enlarged her territory in a series of wars since becoming independent in 1919—including at Munich, where she had seized Czechoslovak territory alongside Germany and Hungary.

Britain’s mixed messaging had devastating consequences. Despite having helped ensure that negotiations between Warsaw and Berlin over the “Polish corridor” would go nowhere by stiffening Polish resistance to Hitler, Chamberlain’s guarantee to Poland was not backed up by shipments of arms, warplanes or even loans. After the German invasion on September 1, all France offered Poland was a brief excursion across the German frontier; Britain dropped a few bombs on the Baltic coast. Shamefully, Poland was left alone on the battlefield as German armies invaded her from five different directions—until September 17, when Stalin’s armies invaded her from the east, completing her destruction.

Poland’s fate during the world war is almost too terrible for words. Her people endured horrendous repression under both Nazi and Soviet occupation, mass executions, forced labor and death camps, culminating in the Holocaust, and then Soviet occupation again, lasting for decades. Anyone who doubts what resistance meant for Poland should examine photographs of Warsaw upon its “liberation” in January 1945: a post-apocalyptic, depopulated pile of rubble, its population reduced from a prewar 1.3 million to perhaps 150,000 survivors.

The parallel to Ukraine today is not exact, but there are eerie similarities which urge caution. Putin is no Hitler, but he has certainly displayed irredentist designs on former Soviet Russian territory, from the war with Georgia over South Ossetia and Abkhazia in 2008 to Russia’s annexation of Crimea and her unofficial moves into Lugansk and the Donbass in 2014.

Like Britain and France with Poland in 1939, the U.S. has taken on Ukraine as a cause, dangling the prospect of NATO membership before her as early as 2008, supporting the “Euromaidan revolution” of 2014 which toppled a Russia-friendly government in Kyiv, and talking loudly of the need to defend Ukraine—Ukrainomania is bipartisan in Washington, one of the few issues which aligns and excites everyone who matters. When Putin finally struck this February, Russia invaded Ukraine from five directions, with Russia’s axis of advance bearing an unmistakable resemblance to the multi-pronged German invasion of Poland in 1939. Once again, despite promises of military support, Ukraine’s main sponsor has left her alone on the battlefield.

There are important differences, too. Poland also faced a Soviet invasion from the east in 1939—a sixth front on top of the first five—whereas Ukraine has nothing to fear from western NATO-member neighbors Romania, Slovakia, Hungary, and Poland. Britain and France never did get arms to Poland in 1939, whereas the U.S. has sold Ukraine Stinger and Javelin missiles.

Putin, indeed, has a much stronger casus belli over western meddling in Ukraine than Hitler did in Poland. Britain and France had far less pull in the Warsaw of summer 1939 than the overweening influence U.S. has enjoyed in Kyiv since 2014. Putin’s claims about Ukraine committing “genocide” in the Donbass may be far-fetched. But his complaints are more credible that Western military and intelligence have turned Ukraine against the historic identity it long shared with Russia, making the country a lethally armed cat’s paw of the West – though not lethally armed enough to deter Russian aggression.

It is not as if no one knew about the dangers. From Henry Kissinger to Zbigniew Brzezinski to George Kennan, experienced American statesmen have warned that even talking about Westernizing Ukraine through NATO might be fatal to peace. As John Mearsheimer cautioned us in September 2015, “the West is leading Ukraine down the primrose path, and the end result is that Ukraine is going to get wrecked.” Mearsheimer’s prescient speech has received 21 million views on YouTube, almost half in the last few weeks, with Washington insiders and media poohbahs excoriating him as a Putin apologist, even as a petition campaign was launched to get Mearsheimer fired from the University of Chicago. We would have better off heeding his warning.

Compounding the damage, Washington’s loud championing of the Ukrainian cause has recently been accompanied by contrary signs of weakness and appeasement, from the humiliating botch of the NATO withdrawal from Afghanistan last summer to President Biden’s hint that a “minor incursion” into Ukraine might not occasion a decisive response. Like Chamberlain veering between irrational extremes in 1938-1939, the West’s Ukraine policy has blatantly provoked Russian anxieties and offered Ukrainians the false promise of an American security umbrella, while doing nowhere near enough to actually deter Russia. Ukraine may not suffer as badly as Poland did from 1939 to 1945, but much of the country has already gotten wrecked.

Ukrainians facing a bleak future might take solace in the fact that Poles can stand tall today, proud of their history of resistance to the terrible joint invasion by Nazi Germany and Soviet Russia in 1939 even while their western allies left them in the lurch. But Poland was never compensated: no reparations were ever paid by either Russia or Germany, the latter of which refused Warsaw’s request for compensation as recently as 2017. And we should not forget that, owing to lasting Soviet occupation, it took Poland nearly seventy years to recover.

It is instructive that Poland’s Prime Minister, despite warmly welcoming in Ukrainian refugees from Russia’s war, has unequivocally contradicted reports that Poland would allow aerial sorties against Russian forces to be launched from her airbases. Poles know in their bones what war really means, along with the consequences of a Russian invasion and occupation.

We might learn from Poland’s example, doing our best to alleviate suffering on the ground rather than escalating tensions further. If a no-fly zone is declared over Ukraine, as irresponsible members of Congress are now proposing, we risk starting a shooting war with Russia, with unforeseeable consequences. All this belligerent talk—in the economic sphere, we are already at Defcon 2, and U.S. Senators are threatening to assassinate Russia’s President—may make westerners feel good, but threats of retaliation do nothing to help Ukrainians. Deterrence failed to prevent Putin from invading Ukraine, but serious negotiations now may save her people from still worse horrors to come.