Tallinn, Estonia

In the 20th century, few nations suffered as much as the Baltic republics—Estonia, Latvia, and Lithuania. Their brief taste of freedom, made possible by the collapse of the Russian Empire in 1917-1918, was snuffed out in 1940 when Russian armies marched back in, this time under the banner of the commissars rather than the czars. When the German Army invaded the following year, many Balts saw them as liberators. But the cruel nature of Nazi rule soon became apparent. The Germans carried out genocide against the substantial Jewish population, a project in which some Balts unfortunately assisted. The return of the Red Army in 1944 brought no respite, with the Communists shipping tens of thousands of people to the Gulag. In all, more than a million people were killed in the Baltic states during World War II, representing nearly 20 percent of the prewar population of 5.4 million.

And of course the suffering did not end in 1945. For decades to come, the Balts were to be occupied by a totalitarian state whose will was enforced by the Red Army and the ever-pervasive secret police, the KGB (and its predecessors). Dissent was ruthlessly crushed. The economy was wrecked by collectivization. Religion was suppressed.

The Balts finally emerged from the Soviet prison in 1991, and in the quarter-century since, they have made nearly miraculous progress. All three countries are members of the European Union and NATO. They are all tolerant, liberal, free-market democracies that enjoy a standard of living higher than Russia's in spite of the absence of any natural resources such as the oil fields that fuel the Russian economy. (Russia's per capita GDP is $25,400; Estonia's is $28,600.)

To walk around their capitals, Vilnius, Riga, and Tallinn, as I did in early June in between meetings organized by the Jamestown Foundation with local political and military leaders, is to experience clean, modern European cities full of delicious restaurants, upscale bars, and chic hotels. The inhabitants are polite, speak English, and revere the United States. Indeed, many of the Balts I met had attended American universities ranging from the U.S. Air Force Academy to Georgetown. All three capitals have experienced a post-Communist building boom while also doing an impressive job of preserving their storybook Old Towns, which look as if they could have sprung from a Hollywood back lot. The only overt reminder of the grim past can be found in Museums of the Occupation, which chronicle the horrors inflicted upon these lands in the past century.

Yet the Baltic achievement remains as fragile as it is impressive. While Lithuania, Latvia, and Estonia in many ways feel like Denmark or the Netherlands, they can never forget that just across their borders lies the Russia of Vladimir Putin. This is not the Stalinist state of cursed memory but nor is it the more liberal regime of Boris Yeltsin in the 1990s. Putin is an increasingly repressive dictator who, unlike his Communist predecessors, is not restrained by the need for unity in the Politburo. He runs Russia as his personal fiefdom, and it is a fiefdom that has been expanding under his rule. Putin has invaded Chechnya, Georgia, and Ukraine. He has illegally annexed Crimea—a forcible change of borders unknown in Europe since 1945—and he has sent his troops to prop up the murderous Assad regime in Syria.

Ever since Russia's invasion of Ukraine in 2014, the fear has been that the Baltics could be next. Given Putin's proclivity for posturing as a defender of supposedly oppressed ethnic Russians, Latvia and Estonia especially have reason to be nervous. They both have large Russian-speaking minorities—numbering more than 550,000 people in Latvia (28 percent of the population) and more than 320,000 in Estonia (25 percent). By contrast Lithuania has only 175,000 Russians—6 percent of the population. The good news is that most of these Russian-speakers know they are better off where they are than under Putin's kleptocracy. The bad news is that local sentiments may not matter if Putin decides, as he did in eastern Ukraine, to manufacture an insurgency out of whole cloth.

Putin is making his intentions clear on a regular basis. His Russian-language TV channels broadcast a steady diet of propaganda into the Baltics, playing up Russian grievances and accusing the democratically elected leaders of those states of being fascists and Nazis—the same nonsense that was used to justify Russia's invasion of Ukraine. Russia is also rumored to be providing funding to Russian political parties in Estonia and Latvia, and mysterious calls are circulating online to recognize "people's republics" among the Russian minorities. NATO generals believe that we are already seeing "Phase One" of a Russian "hybrid war" against the Baltics, playing out primarily in the realm of information warfare and cyberwar for the time being.

If an actual shooting war breaks out, Putin will be ready. He has been expanding and enhancing his forces in the Western Military District of Russia. This area now has an estimated 65,000 Russian troops, 850 artillery pieces, 750 tanks, and 320 combat aircraft, all located just a few miles from the Baltic borders. The Balts have gotten used to no-notice "snap" exercises that involve tens of thousands of Russian troops maneuvering nearby—exercises that could easily be employed in the future as a pretext for an actual invasion.

Russia has also flexed its muscles in other ways. It has been sending submarines to violate Swedish territorial waters and aircraft to penetrate Baltic airspace. On April 11, two Russian SU-24 jets buzzed the destroyer USS Donald Cook in international waters in the Baltic Sea at an unsafe altitude of just 100 feet. Earlier, on September 5, 2014, Russia's FSB security service kidnapped an Estonian intelligence officer on Estonian soil. He was then convicted of espionage and sentenced to 15 years in prison before being released last September in exchange for a Russian spy in Estonian custody. All of these events, seemingly unrelated, serve as a not-so-subtle warning from Putin that he is the master of the Baltic and can do what he likes there.

As part of this strategy, Putin has heavily militarized Kaliningrad, the former Prussian city of Königsberg, a Russian naval base which lies on the Baltic coast between Poland and Lithuania. It now hosts more troops (30,000) than all of the Baltic states combined can deploy—and, more important, it also hosts advanced air defense systems (the S-300 and S-400), Kaliber antiship cruise missiles, and mobile surface-to-surface Iskander ballistic missiles. Western military strategists fret about the A2/AD (anti-access, area denial) threat posed by the Russian missiles. They could turn the Baltic Sea into a no-go zone for NATO warships and aircraft, allowing Putin to digest the Baltics at leisure.

The only land connection between the Baltics and other NATO countries is a 60-mile-wide corridor running from Poland to Lithuania. On one side is Kaliningrad, on the other Belarus, a nominally independent dictatorship that was once a Soviet republic and is still closely aligned with Russia. Belarus could find itself ripe for Anschluss if Putin wants another easy victory to buttress his popularity at home. But even if Belarus remains nominally independent, Russian troops are likely to move freely over its territory. NATO generals now talk of the Suwalki Gap (Suwalki is a small Polish town at the midpoint of this land bridge) the way they talked during the Cold War about the Fulda Gap (the likely invasion route for the Red Army from East Germany into West Germany).

These geographic vulnerabilities are all the more worrisome because of plentiful evidence that Russian military capabilities have vastly advanced not just since the 1990s but also since the 2008 invasion of Georgia, which, although successful, revealed plenty of shortcomings among the low-quality conscript forces that Russia relied upon. Since then, Putin has been pouring large amounts of money into modernizing his military and converting it into a professional force. According to the Stockholm International Peace Research Institute, Russian defense spending in 2015 increased by 7.5 percent to reach $66.4 billion. That makes Russia the largest military spender in Europe and one of the largest spenders on a per capita basis in the world—Moscow spends 4.5 percent of GDP on defense, compared to 3.5 percent for the United States. Though Russia may lag far behind us in total spending (the United States has a defense budget of nearly $600 billion), it has the luxury of focusing its forces on its frontiers, while we contend with multiple security threats around the world.

Russia's ongoing intervention in Syria has been used by Putin as a showcase for his new toys, such as the Kaliber cruise missiles that were fired by Russian warships in the Caspian Sea at targets a thousand miles away in Syria. "We're quite impressed with their capabilities," a Latvian security official told me. That's exactly the reaction that Putin wants.

Beyond its conventional forces, Russia still possesses the world's second-largest nuclear arsenal, and its leaders have not been shy about threatening to use it. As a Polish think tank has noted:

In May 2014, [Dmitry] Rogozin [Russia's deputy prime minister], reacting to being barred from an over flight of Romanian territory, tweeted that the next time he "will fly on board" a Tu-160 strategic nuclear bomber. In August 2014, the vice speaker of the Russian Duma, Vladimir Zhirinovsky, threatened nuclear use against NATO member states, declaring that "the Baltic States and Poland are doomed," and that they "will be wiped out" and "nothing will remain there." Earlier, in March 2014, another controversial figure, Rossiya 1 news channel television anchor Dmitry Kiselyov, vividly explained that Russia is the only country capable of turning the United States into "radioactive ashes."

Even in Soviet times, the Kremlin refrained from threatening to nuke its neighbors as bluntly as it is now doing.

But of course Russia doesn't need to employ its nuclear arsenal or even its tanks to bully and defeat its neighbors. The Ukrainian conflict showcased the "little green men," plainclothes Russian soldiers and intelligence operatives pretending to be indigenous rebels. This has given Russia a degree of deniability in its aggression and has prompted anguished debate in NATO circles over what it would take to invoke Article V of the 1949 North Atlantic Treaty, which calls on NATO members to come to one another's defense when attacked.

In the face of this escalating Russian aggression, the Western response has been improving but remains inadequate. The Baltic republics themselves are boosting their defense budgets and increasing the size of their armed forces. Latvia's parliament voted unanimously this year to increase defense spending by 45 percent. "We are not free riders," a Latvian politician proudly told me, a reference to the accusation made by President Obama against America's European allies.

It sounds impressive—but Latvia is still spending only 1.4 percent of its GDP on defense, below the NATO guideline of 2 percent. Latvia and Lithuania will reach the 2 percent threshold in 2020; Estonia is already there and continues to expand its defense budget. For now the three Baltic states combined spend $1.56 billion annually on defense—about what the Pentagon spends in a single day.

To say that the Baltic armed forces are tiny is an understatement: Together, they have fewer than 20,000 active-duty troops and 36,000 reservists. Lithuania is trying to boost its numbers by reinstating conscription, which Estonia already has instituted; Latvia continues to rely on all-volunteer forces. The Balts have no combat aircraft, no air defenses, and no tanks. Instead they are relying on niche capabilities, such as Javelin antitank missiles, to slow down invading Russian tanks.

There is more they can and should be doing. Consider the case of Israel, another state whose existence is threatened by its neighbors. It has 160,000 soldiers in its active-duty forces and 630,000 in the reserves, supported by one of the largest and most effective air forces in the world. Israel's defense budget is $15.6 billion. Granted, Israel is larger and wealthier than the Baltic states: Its population is 8 million, compared with 6.2 million for the three Baltic republics, with a GDP of $296 billion, compared with the Balts' $90 billion. Israel also receives a lot more American aid—more than $3 billion annually.

But there is no getting around the fact that Israel does more proportionally than the Balts do: The Jewish state spends 5.9 percent of its GDP on defense and keeps nearly 10 percent of its population in the reserves or in the regular forces. The comparable figures on spending and manpower for the Balts are less than 2 percent. Even Finland, which shares its own lengthy border with Russia, does more: With a population of 5.4 million, it has a standing army of 20,000 and reserves of more than 200,000 men.

The Balts need to spend more on defense, especially to expand their reserves. The most effective way forward would be to pool their efforts. Their failure to do more to coordinate their defense policies makes it impossible to achieve economies of scale that could come from procuring weapons systems jointly. Washington should press for more joint military procurement and operations among these three states. The Balts would be even better off if they could create a single, unified state or at least a single, unified military force, but that seems unlikely given the cultural and historical differences among them. The Lithuanians are Catholics with close ties to Poland; the Latvians and Estonians are Lutherans with closer ties to Sweden and Finland. All three states cherish their sovereignty, which was lost for so many decades.

In talking with Baltic leaders, a certain fatalism can creep in. They know there is no way their tiny countries can defeat Russia (population 142 million) in an all-out war, whether singly or jointly. "Even if we spend everything we have, we can never defend ourselves," a Lithuanian leader glumly told me.

But simply having large pools of trained and armed reservists could help to deter Russian aggression. Putin prefers quick coups like the one he pulled off in Crimea, where the Ukrainian forces did not fire a shot. The last thing he wants is a prolonged guerrilla war in the marshes and forests of the Baltics, where Stalin faced armed resistance during the 1940s and early 1950s. If the Baltics can credibly threaten Putin with the prospect of Russian soldiers coming home in body bags, they are less likely to be invaded. Latvia is trying to do just that by making it illegal for its military commanders not to fight back if their country is invaded. There will be no repeat of 1940, the Balts vow, when they allowed the Red Army to walk in uncontested.

In the final analysis, however, the Balts are mainly right—their fate depends less on their own exertions than on those of their NATO allies. There is only so much they can do to stand up to the bear next door; if they are to survive, the United States and other NATO countries must contribute to their defense. That is now happening—albeit not yet at a sufficient level.

In Estonia, for example, I went with a delegation from the Jamestown Foundation to visit Amari Air Base, where NATO is undertaking an air policing mission. We found four Royal Air Force Eurofighter Typhoons, aircraft roughly equivalent to the F-15, based there as part of a rotation among NATO members. The fighters regularly scramble to investigate and ward off Russian military aircraft that operate near Baltic airspace with their transponders turned off.

There is also a company of U.S. soldiers—roughly 150—deployed in each of the Baltic republics and Poland. A NATO Very High Joint Readiness Task Force, equivalent to a brigade, is supposed to be ready on short-notice to come to the aid of the Baltics, but NATO officials admit it does not have the capability to tangle with conventional Russian forces even if the ponderous North Atlantic Council could reach a decision to use it in time.

NATO troops now conduct regular exercises, such as Anakonda 16 in Poland this month, to deter the Russians, and American armored personnel carriers and tanks have been driving through Eastern European states on "dragoon rides" in a similar signal of resolve. If nothing else, U.S. forces are learning the lay of the land, something that will be of great value should a war ever break out.

The NATO Summit in Warsaw on July 8-9 is expected to approve the deployment of additional NATO battalions, one in each of the Baltic republics and Poland, for a total of 4,000 troops. But will they be real fighting units or multi-national forces long on symbolism and short on combat effectiveness? Given NATO's checkered track record, it is hard not to suspect the latter. If so, it will only place additional importance on what the U.S. does unilaterally.

As part of the European Reassurance Initiative, the Obama administration is planning to spend $3.4 billion this fiscal year to fund more U.S. troop deployments and exercises in Europe. One additional U.S. Army armored brigade will regularly rotate through Europe, boosting the total number of U.S. Army brigades on the continent from two to three, and equipment sufficient to equip another armored brigade will be pre-positioned on the continent, probably in Germany.

That is better than nothing, but it is still insufficient to credibly deter Russian aggression. A RAND Corp. war game recently concluded that Russian forces could overrun the Baltics in as little as 36 hours, and U.S. commanders themselves admit they do not have the bare minimum of forces necessary to deter, much less defeat, the Russians.

What might a more serious response look like? Put at least one armored brigade in each Baltic country and Poland along with at least one Combat Aviation Brigade for the region. Then put in a division headquarters and a corps headquarters to coordinate these brigades and other forces in Europe. It is critical that a substantial number of these troops be American because, as the Balts remind anyone who will listen, the Russians respect American capability and willingness to fight far more than they do the Europeans.

That makes it all the more worrisome that the U.S. Army companies currently deployed in the Baltics might be withdrawn once the multinational NATO battalions arrive. Instead of drawing down the U.S. forward presence, Washington should be expanding it, and those troops should be backed with additional air defenses, aircraft, and ships. Should the worst happen, NATO forces must be able to fight through the A2/AD "bubble" around Kaliningrad to deliver the aid that the Balts would need in wartime. There is no reason NATO cannot permanently station substantial forces in the Baltics and other Eastern European states, as a careful reading of the 1997 NATO-Russia Founding Act shows.

To deter a Russian attack on the Baltics, the West should take other steps to demonstrate that aggression does not pay. At a minimum, the United States should send arms to the Ukrainians, who are still fighting Russian-backed forces in the east, and ramp up sanctions against Russia. The most effective move would be to kick the Russians out of the SWIFT system of interbank transfers and to freeze the funds held by Putin and his cronies in the West.

Simply to state the requirements is to suggest how unlikely they are to be realized in the current political climate, with the U.S. defense budget falling and U.S. commitments growing in East Asia and the Middle East. The talk in Europe is of when to lift sanctions on Russia, not how to double down. And the will of the West could become even more attenuated before long.

The Balts are nervously eying two elections: the British referendum on leaving the European Union, known as Brexit, on June 23, and the American presidential election on November 8. They are deathly afraid that Britain will leave the EU and that Donald Trump will win the presidency of the United States.

The mantra from the Balts I spoke to is that they want the United Kingdom to "lead, not leave" the European Union. They see the Brits as kindred spirits, because they are more market-oriented and more pro-American than the Germans and French. If the Brits leave the EU, the Balts fear Europe will veer off in a more protectionist and statist direction.

Beyond that, the Balts are keenly aware of the need for European unity in the face of the Russian threat. A British exit from the EU could lead other countries to depart and might even lead to the collapse of the entire common European project. NATO would still survive, of course, but at the very least the British and other Europeans would be distracted with internal concerns—what kind of relationship should the U.K. have with the EU post-Brexit?—rather than focusing on the external threat from Russia. "The political spillover of Brexit would be terrible," a politician in Lithuania told me.

A Trump victory in November would deal an even more severe blow to the future of the Baltics. An isolationist and a protectionist, Trump has spoken fondly of Vladimir Putin, a man with whom he imagines he could make great deals, while speaking harshly of America's traditional allies. Trump has said that NATO is "obsolete" and has promised to withdraw U.S. troops from any countries that don't pay enough for the privilege of being defended—which in his estimation includes pretty much every country where U.S. troops are currently deployed. "Why are we always paying the bills to protect other people?" Trump demands to know.

The answer is that we have seen what happens when we don't. The isolationism of the 1930s led directly to World War II, a conflict that proved to be the second-most costly in American history. The rise of Nazi Germany, Imperial Japan, and Fascist Italy might have been avoided, and war averted, if Washington had made a concerted commitment to security in Europe and Asia after 1918. Learning its lesson, the Greatest Generation did not pull U.S. troops out after 1945. As a result, another world war was averted, liberty was expanded, the Soviet Union was contained, and the Cold War was ultimately won.

No doubt if Trump had heard of the Baltics (which all too many Americans confuse with the Balkans), he would demand to know why we should risk a single American soldier in order to preserve their freedom. Because we promised to do just that in 2004 when these states were admitted to NATO, and if NATO does not honor its commitments, it will be kaput. Indeed, that is precisely why Putin may be tempted to move into the Baltics: He knows that a successful incursion could lead to the end of the Atlantic Alliance.

Should collective security collapse, there is no reason to imagine that Putin would end his aggression in the Baltics. If history has shown anything, it is that dictators keep going until they are stopped. Russian domination of Eastern Europe, much less of Western Europe, is a risk that the United States cannot afford to run, given the economic and strategic importance of the continent. (Trade between the United States and EU in goods and services amounts to more than $1 trillion a year.) It would be immoral as well as just plain stupid for the United States to abandon these close allies. But in order to protect them properly, the next president will need to do more than the current one has done.

Max Boot is a contributing editor to The Weekly Standard and a senior fellow at the Council on Foreign Relations. He is the author most recently of Invisible Armies: An Epic History of Guerrilla Warfare from Ancient Times to the Present .