I’m standing in an air base in northeastern Romania looking at the incontrovertible truth that there’s something different about Russia’s aggression this time: the NATO Very High Readiness Joint Task Force, aka the men and women responsible for stopping World War III. The task force, a “spearhead” of the free world's military, has been deployed for the very first time. “Two hundred nautical miles away, there’s a hot war going on across the Black Sea right now,” U.S. Army Maj. Gen. Matthew Van Wagenen tells me. This plot of land — MK Air Base, outside the resort city of Constanta, and the front-line NATO countries of which it's a part — “this is the edge of freedom.”

In any given year since the VJTF was created, one country has to keep soldiers ready to deploy as quickly as possible, while another trains to take over the next year. This year, it’s a joint French-Belgian group, 800 soldiers who got here in two days and five days, respectively, after they got orders. The French flew in their tanks, and the Belgians drove theirs on a massive truck convoy across Europe. In the tents where the French and Belgian Very High Readiness Task Force members actually live, it smells a little like sweat. The Belgian and French barracks tents are arranged in rows, with a few supplemental Dutch tents off to the side. The French and Belgians have separate tents for the female soldiers, but the Dutch, thinking that prim, sleep coed. Nico, a French paramedic driver of an armored personnel carrier ambulance, sits at a table across from the rest of his unit as they take apart, oil, and put back together a .50-caliber machine gun. On the wall, there’s a map of Ukraine, with the areas of high conflict shaded red, and another chart of their upcoming exercises. Last week, they did a training exercise near the Ukrainian border in Smardan, Romania, with American forces involving artillery, among other things learning NATO procedures and practicing commands in English. This week, they are off for Orthodox Easter, and the week after, it’s tank exercises with Belgians and the Polish. Nico says they spend a normal day doing three things: “Practicing, practicing, practicing.” Their families, someone says, are worried about them here. “We left a bit fast, because when we were deployed, we had 24 hours to say goodbye. It was a bit stressful for them. But they are proud.”

Seven nations have forces just on this Romanian air base, which has swelled from a few hundred to over 3,000 personnel over the last few months. Task Force Tiger, as this deployment is called, is a frenzy of activity. Italian Eurofighter Typhoons pull tight circles overhead to get downwind of the runway while French soldiers clean their guns and Americans shoot hoops. There are two mess hall tents, stocked by some very nice ladies from Hawaii and Florida, now cooking here for the men and women who are spending their days defending the southeastern flank and pouring shockingly good jalapeno ketchup onto shockingly bad turkey burgers.

I ask Vincent Manguet, the commander of Task Force Tiger, what the closest NATO battalion is to the conflict in Ukraine. “It’s us right now,” Manguet says.

First, though, NATO insisted I understand the big picture. So, before the edge of freedom, and before my stop before Romania — a few days in Estonia to watch a NATO training session called Operation Bold Dragon — is a trailer in Belgium, where the plans to prevent World War III are made.

Well, it’s not quite a trailer. There’s a massive underground bunker facility built to resist a nuclear strike, and the Special Operations Command building feels pretty permanent. But most of the military headquarters of the North Atlantic Treaty Organization, the Supreme Headquarters of Allied Powers Europe in Casteau, outside the medieval city of Mons, is made up of a labyrinthine system of those modular, rectangular temporary offices like the ones you might run a construction site from. There are hundreds of them comprising the cafeteria and the rooms where war plans for apocalyptic, worst-case nuclear war scenarios are thought through so they can be avoided, and the offices of the job first held by Dwight Eisenhower, Supreme Allied Commander Europe.

NATO, being the most powerful military alliance in the history of the planet and a political organization of 30 countries that requires unanimous consent to do anything, is also broadly misunderstood, thanks in part to Vladimir Putin’s complaints of its presence in countries near Russia. History is a better guide than an authoritarian kleptocrat: On the occasion of the Operation Dynamo evacuation of British forces from Dunkirk, Winston Churchill gave one of history’s great speeches, concluding with a defiant and gloomy optimism that “we shall never surrender, and even if, which I do not for a moment believe, this Island or a large part of it were subjugated and starving, then our Empire beyond the seas, armed and guarded by the British Fleet, would carry on the struggle, until, in God’s good time, the New World, with all its power and might, steps forth to the rescue and the liberation of the old.” And in God’s good time, perhaps too much time, it did. American forces have never left Europe since the D-Day landings in June 1944. British Gen. Lord Hastings Ismay, who was part of the planning for both the Dunkirk and the Normandy operations and became after the war the secretary-general of NATO, is the most frequently quoted summarist of the alliance’s purpose: “to keep the Russians out, the Americans in, and the Germans down.”

“NATO’s never been more important,” Van Wagenen waxes in Romania. As for America, he’s proud of what he sees as his country’s large but deeply worthwhile sacrifice, which is an investment in peace as well as a matter of honor, payback for the NATO allies' principled choice to fight with America when we called: “It was the other 29 countries in NATO that stood with the U.S. in Afghanistan.” What about the complaints that NATO, by subsidizing other countries’ defense, is making chumps of Americans? The general points out World War II cost a lot more than any peacetime deterrence policy. “NATO’s like your car insurance. You pay a hundred dollars every month, and as you drive your car around, if nothing happens, it’s easy to believe, as long as you never crash, you didn’t need it. But then someone wrecks into you. So, it’s an investment in security, and probably right now, it’s going to be the No. 1 thing that keeps the Russian Federation out of places that they’ve openly stated that they want to get into.”

Russia’s brutal invasion of Ukraine has been cause for reflection on NATO’s purpose, much of which has confirmed its raison d’etre.

“I joined NATO out of conviction,” Lt. Gen. Brice Houdet, a former French Legionnaire who’s been deployed to eight countries, tells me in his office in Belgium. “I am personally convinced that NATO is a peace factory.” He is furious at what he sees happening in Ukraine, “the behavior of the cave age,” and says that “people watching on smartphones are realizing that peace is an invaluable treasure.” This is the guy who is responsible for the rapid reaction corps at the highest level, who designs deterrence policy, explaining that deterrence means having the capacity to make war and communicating what one is willing to do with it very intelligently and carefully, and meaning it. “To preserve peace,” he tells me, involves two things. “One, you need capabilities.” “You need to show your adversaries that the costs will be higher than the benefits. What gives you a strategic advantage? Very powerful weapons.” But also, the second thing it takes to keep peace: “Morale, conviction, will to fight. … You have to be willing to die and to give death to defend your loved ones, your culture, and your principles.”

Since the invasion of Ukraine, NATO has increased its presence in Eastern Europe’s front-line countries that border Russia or Belarus by 40,000 troops, by over a hundred aircraft, and by over 25 ships. And NATO really wants to stress that they are there to prevent or repel an invasion, not to mount one. Deterrence is, at its very core, simple enough that we all learn it on the playground. If you say, “Don’t hit me, or I’ll hit you back,” to a bully, you had better be believed. And if you do get hit anyway, you actually do have to hit back. But just having a plan to respond doesn't make you the aggressor. This is why Russia’s claims to have been “provoked” by NATO through things like its 2004 expansion to include seven more countries ring hollow.

One of those seven countries, Estonia, was my next stop.

Estonia is one of the few countries that fulfill NATO allies’ promise to spend more than 2% of GDP on defense. As of a month ago, Estonia was giving more weaponry to Ukraine than Germany was, despite being 1/80th its size. People here think about Russia a lot, as this was a Soviet satellite until only three decades ago, and now, it is a shining metropolis and global tech hub, where AI robots roam the streets making deliveries and the quality of life is as high as anywhere in the world. In the historic old city of the capital, Tallinn, one of the main tourist attractions is the old KGB prison, from the bad old days. And two blocks away, Estonian police are dutifully guarding the Russian Embassy, outside of which Estonian protesters have placed all kinds of lewd and abusive and hilarious posters expressing how much they hate Vladimir Putin.

Not quite halfway into the drive from Tallinn to St. Petersburg, if you head south, you will get to Tapa Central Training Area, a 46-square-mile facility where I have been invited to watch a 10-day training exercise in which the NATO forces deployed here are getting certified to work together and with the Estonians. It’s huge, with hundreds of men from French, Danish, British, and several different types of Estonian forces, plus Belgian F-16s overhead. If you forget that the Russian border is just over there, and if you have a heated car with you, it’s also kind of fun.

But it is deadly serious. As I pull in, in the first battlefield I come upon are the war game’s defensive forces repelling the joint French-British-Danish “invaders,” a freezing-cold, wind-whipped trench of Estonians from the Territorial Defense League. Almost 500 of these men and women are here, giving up their weekend to sleep in the snow so they can learn how to complete their mission. Today, one tells me from behind a massive cannon, that mission is to “kill some tanks!” Some of the Estonian soldiers have newly made, unofficial “Slava Ukraini” arm patches next to their own insignia, referring to the “glory to Ukraine” slogan used as a rallying cry and more recently a military salute. Here, the generational gap really makes itself seen. Young Estonians could be Brooklynites, but the older ones show almost physical signs of having lived under Soviet rule. Both, though, know what they’re here for. “Javelins ready, we are waiting for them.” That would be the Javelin Advanced Anti-Tank Weapons System. Each shot from a Javelin, a British soldier tells me, “is like launching a Porsche. It’s $100,000 a shot.” There are full-time professional Estonian soldiers here as well, both conscripts and career servicepeople.

Over the course of the day, I get to meet French commanders who are plotting to overrun the Defense League, fake fighting with the Estonians to train both how to work together and how to fight more effectively. I meet the British soldiers who take hilltops with rocket launchers so that their colleagues in tanks can round corners without getting blown up. I meet an Estonian psyops specialist, maybe 22 years old, who is running around in a Mercedes G-Class, setting up a high-tech system of speakers that makes it sound for all the world like a large tank column is approaching through the woods, in the complete wrong direction. He smirks a lot. “We have a border with Russia, and they are not very polite,” someone with a heavy machine gun explains to me with the Estonian sarcasm it takes a while to get. Cruising from area to area, there’s an English-language “forces station” on the radio, a reminder we’re not far from the city, and in a country that has to get used to hosting a lot of allied forces to stay safe.

On the other side of Estonia sits Amari Air Base, where a few days after Bold Dragon, there’s another NATO exercise called ALLOY, this one in the air. I’m here to learn about NATO air policing, as they call it. “As a NATO member, you have rights, but you also have duties to fulfill,” says Blanky, the nickname of the Belgian battalion commander here, and also a pilot. In front of us are one Belgian F-16 and one French Mirage 2000. They are here doing QRA, or quick reaction alert, missions, and they get close to Russian jets on a “weekly, sometimes daily, basis.” Their job is to be able to get in the air fast, in under 15 minutes. Blanky brags that it never takes them even that long. Today, Czech Gripens, Finnish F-18s, Belgian F-16s, and French Mirages from as far away as Ramstein in Germany are meeting in Estonian airspace to practice a training scenario in which they protect the skies, miming aerial combat. The fighter pilots are both repelled by and fascinated to live to see actual dogfighting going on so nearby. “It’s a strange feeling,” French Mirage pilot JC tells me, “because you are watching something which you didn’t want to happen. But at the same time, it is one of the first times we are having the opportunity to do what we have been trained for.”

Three jets do a close flyby overhead, turning tightly. With all these missions, the engineers have been busy, and Quentin, a French fighter jet mechanic, has a sense of humor about it. “It’s basically like a computer; most of the time, you shut it down and turn it back on again, and it works.” He worked at Renault, the car manufacturer, until he was 24, but he has loved jets since he was 6 and says he does this job to impress the little boy version of himself.

NATO’s self-defense clause, Article 5 of the treaty, can be invoked by any member, and with the consent of the alliance’s council, every member is then obligated to contribute to defending whoever has been attacked. It’s only happened once, on Sept. 12, 2001, when NATO’s biggest and most important member invoked Article 5. Every NATO ally honored its collective defense promise and contributed to the effort in Afghanistan in one way or another. Many lost troops. Partly for this reason, it would have been unthinkable on Feb. 23, 2022, the day before Putin’s tanks and missiles and infantry started crossing the border of Ukraine, to read the news that Sweden and Finland are moving toward applying for NATO accession. The two countries have different reasons for having stayed out, but both weighed their commitment to neutrality as way more important than their need for NATO’s guarantee of collective defense. War has a way of changing things. Vladimir Putin has done what no amount of debate from pro-NATO politicians could have: made it blindingly obvious that it’s better to be inside NATO than not, if you’re a country Russia has historically invaded.

“Our major secret weapon is to deprive you of an enemy,” joked Georgi Arbatov, an adviser to Mikhail Gorbachev, at the end of the Soviet era. NATO itself has been undergoing something of an identity crisis, arguably since the end of the Cold War but certainly for the past nine months, since its mission in Afghanistan ended. It was a damaging moment for the alliance, and for a lot of the people in it. Some 300 children had been hoisted over the fences and passed through the masses at Kabul airport as Afghanistan went to pot, a German air force member who'd been there a dozen times told me. Many were passed across to a world with no uncles or aunts, no contacts of any kind — the desperate act of parents who knew they were not going to get out of Afghanistan themselves, did not know what their country would look like without coalition forces to deter Taliban domination, and made the unthinkable calculation that their children were better off without them, unknown to them, but safe in the West. Today, they’ve all been processed and found homes, and now, NATO, reeling after Afghanistan, is coalescing around a new mission that’s in many ways more traditional and institutionally central for it: the defense of Europe from Russia. In Estonia, Lt. Col. Rupert Streatfeild explained to me the same thing several other high-level officers did: Russia’s invasion is a horror to watch, for them as it is for all decent people, but for them at least, it reminds them why they do what they do: “Most of our officers were born after the Cold War ended. It’s given a sense of purpose.”

I hear that again in Romania, this time from a Belgian commander, Maj. Florent (who asked me not to use his surname). “Honestly, it’s much more difficult for the families at home than for us here. They are watching TV from Ukraine, they are worried about us. Here, we are a group of buddies, and we are just training together, we are learning about other military structures, being on-base with a lot of other countries, a lot of guns, a lot of vehicles, and a lot of ammunition. We are well-equipped, we have a very good base. So, the morale is good, because we are just doing our job.” Ultimately, these forces are here to prevent a bad war from growing into a global conflagration. It’s a strange thing to meet someone who is, at once, just a guy in front of you, explaining his day-to-day life and his thinking and his job, and also the literal embodiment of the plan to stop an apocalypse.

But that’s everyone you meet in NATO, to one degree or another. And Maj. Florent stresses they think in tactical terms, not geopolitical ones. Maj. Florent tells me he and his men are not here “to be first in line just to be invaded and to be attacked and to give a reason or a justification to send more troops. No, it’s not the point. The point is to have a presence with enough force to deter Russia from coming across the NATO border. We have built here a strong and credible force, and we are ready to react in case of transgression of the NATO border.” He reminds me that everyone has a go-bag ready on the floor by their desk, gesturing at the busy command hub offices. Still, he’s confident the bags will end up staying right where they are. “Deterrence is working.”

Which is why Putin’s attempts to play the victim are so transparent, and why it’s easy to believe U.S. Air Force Maj. Gen. Phillip Stewart when he tells me, “There’s no plan that ends in Moscow” — while stressing that there is, however, a plan for every possible defense scenario. Stewart runs something called “strategic employment,” which may sound like a human resources gig but is, in fact, the very highest-level planning job about how to “employ” things like battalions and bombers. One big thing that you should know about talking to NATO personnel, from its top generals to workaday troops, is that they are incredible at what both military and PR pros call “message discipline.” In some 40 interviews for this piece, not one general or soldier failed to stress to me that NATO is a purely defensive alliance — whether I asked or not. They do, however, have feelings, and they have a lot of the same ones about why they do what they do. Stewart is a little tetchy about the old joke that NATO really stands for “No Action, Talk Only,” which he brings up. The thing is, though, this is the contradiction at the heart of understanding NATO, what it does besides sit as ink on a piece of paper, and why people criticize and misunderstand it: When NATO succeeds, nothing happens. When an organization is charged with preventing war, and with waging war should it need to, saying it is characterized by “no action, talk only” is a pretty ringing endorsement of its success. More no action, please.

Nicholas Clairmont is life and arts editor of the Washington Examiner magazine.