There’s no use pretending that the election will turn on either candidate’s foreign policy positions. But there are some people for whom the question of whether the U.S. will remain a dependable ally is more than a theoretical concern. As the New York Times reports today, tens of thousands of Estonians are roaming their country’s forests taking part in war games—games that are largely predicated on the notion their country will be invaded by Russia in spite of America’s obligation under the NATO treaty to come to their defense.

As citizens of one of the three Baltic republics on Russia’s Western border that only regained their independence after the collapse of the Soviet Union, Estonians understand their freedom hangs by a thread. After Vladimir Putin’s invasions of Georgia and Ukraine and the lack of consequences for the annexation of Crimea, the people of Latvia, Lithuania, and Estonia understand the only deterrent to a similar outcome is Article 5 of the NATO treaty, which obligates the members of the alliance to each other’s defense. So when Trump said this year that he wouldn’t automatically defend the Baltics against a Russian invasion in spite of that solemn commitment, the people of Estonia didn’t shrug at just another wacky statement from the GOP nominee; they checked their home emergency supplies.

Trump claims that an inability to predict his behavior would be an advantage to the United States. But that statement demonstrates his ignorance of history. Most wars started because the two sides misjudged each other’s willingness to defend their interests and allies. While the threat of nuclear war prevented the two superpowers from engaging in direct hostilities during the Cold War, the main deterrent to any further Russian aggression against former parts of the Soviet empire is the certain knowledge that the United States takes its treaty obligations in Europe with deadly seriousness. If, due to Trump’s lukewarm attitude toward NATO and oft-expressed desire for warm relations with Putin, that is no longer the case, there is little reason to believe the Baltics won’t suffer the same fate as Ukraine.

Of course, the Estonians didn’t need Trump’s talk about demanding that they pay more for American defense to start worrying about the Russians. They’ve been occupied before and have a long tradition of fighting guerrilla wars against both the Nazis and the Soviets. They know their tiny standing army would be overrun in hours by any Russian invasion. That’s why they’re preparing for an insurgency that would make the lives of the invaders miserable with nationwide “games” in which citizens compete to demonstrate their readiness for a new round of heroic resistance. Estonia’s government has even taken to distributing weapons to be stored in private homes for individual use in the case of war, a measure that should engender the sympathy of Americans who treasure their Second Amendment rights—rooted as they are in the notion that an armed populace is the best defense of the people’s freedom.

But while we may cheer the pluck of the Estonians, let’s not romanticize what they are preparing to endure. If the Russians invade, the suffering of the people of the Baltic republics will be incalculable and no amount of heroism on their part or inconvenience to Moscow’s forces will compensate for the innocent blood that will be spilled. Nor should we harbor any illusions about what would trigger such a catastrophe. If the leader of the free world becomes someone that views treaty obligations as a hinging on bill collections from small countries that depend on American honor for their freedom, the liberty of Estonians, Lithuanians, Latvians and perhaps that of other peoples will be finished.

The Times feature is a sobering reminder of what cavalier comments about NATO entail. To voters to whom Estonia is just, in Neville Chamberlain’s phrase, “a faraway country” populated by a people “of whom we know nothing,” the new “America First” neo-isolationism that Trump has promoted sounds like common sense. But to Europeans thinking about using their gun rights to defend their homes and families against Putin, it sounds like appeasement of a dictator and a betrayal of the peace and freedom that American strength and resolve brought the world in the second half of the 20th century.