Today (Sept. 14), three new countries were born: Veishnoria, Vesbaria, and Lubenia. They will be short-lived, winking out of existence just six days later. They are three fictional states that Russia and Belarus will battle during a massive joint military exercise. They bear a striking resemblance to parts of Latvia, Lithuania, and Poland, the NATO members on Russia and Belarus’s borders.

And NATO, not surprisingly, is nervous.

France’s defense minister has called the exercise, named Zapad, a “strategy of intimidation.” Her German counterpart says they are a “demonstration of the Russians’ capability and power,” and promised that Poland and the Baltics can “count on us.” NATO claims Russia is lying about troop numbers and not allowing enough Western monitors.

Russia holds large war games every year, rotating between the points of the compass; Zapad (“West”), on the Baltic border, was last held in 2013 and before that in 2009. But now is a time of acute insecurity for NATO. US president Donald Trump’s initially watery support for the NATO premise that “an attack against one ally is considered an attack against all” made the alliance’s European members quietly ponder how they’d cope without America’s military ballast.

Meanwhile, Russia has been beating its chest louder than at any time since the fall of the Soviet Union—unleashing propaganda operations across the West, flying sorties into other countries’ airspace, and allegedly hacking the US and French elections. Relations with the US hit a new low after Congress forced Trump to sign a new Russia sanctions bill in July, prompting tit-for-tat diplomatic expulsions.

And just this week, Turkey—one of NATO’s biggest armies—signed a deal to buy a Russian missile system. That’s widely being read (paywall) as a blow to the alliance’s unity. To eastern European governments worried about being targeted for a Crimea-style invasion, the Zapad exercise looks an awful lot like a test run.

But it would be a mistake to take the threat of Zapad too seriously, experts we spoke to say.

Why is Russia conducting the Zapad exercise?

Mark Galeotti, a senior researcher at the Institute of International Relations Prague, says it’s important to remember that Zapad isn’t another tit-for-tat move but one of Russia’s regularly scheduled drills, and that all militaries need to train to stay in shape. But, he notes, it’s also “a massive psychological warfare operation.” It serves as a warning to EU members like Sweden and Finland, which have never joined NATO but are contemplating it. The threat, Galeotti says is: ”If you do join NATO, you will have some Crimea scenarios placed on you.”

It also serves as internal propaganda, says Charles Kupchan, a senior fellow at the Council of Foreign Relations and a former senior US National Security Council staffer. Russian president Vladimir Putin “is continuing to play the ‘I’m your man who can stand up to the West’ card. He doesn’t have much else to legitimate his rule: Russia’s economy is still sputtering along, energy prices remain low, he hasn’t really invested in the knowledge economy.”

How many troops is Russia really mobilizing in Zapad?

Russia says there will be 12,700 troops in the exercises. That’s convenient: As a member of the Organization for Security and Cooperation in Europe, it has to let other countries send observers when it does maneuvers of 13,000 troops or more. The Europeans insist the real number will be more like 100,000, a claim Russia has angrily denied.

In reality, Moscow and Minsk will probably have about 13,000 soldiers in Belarus, but some 100,000 moving around the whole of Russia in a “nationwide readiness test,” suggest Galeotti and Gustav Gressel, a senior policy fellow at the European Council on Foreign Relations in Berlin. In total, Russia’s armed forces are estimated to have somewhere between three-quarters of a million and a million uniformed troops.

Should NATO be worrying about Zapad?

“Officials have enough reasons to be worried,” says Gressel. Exercises in the Caucasus in 2008 were quickly followed by the Russian-Georgian war, while a major 2014 maneuver on the Ukrainian border took place as war raged in the Donbass.

However, while NATO members have made a lot of anxious noises in public, when Kupchan attended a conference with European parliamentarians in Estonia on Sept. 8, he says, people seemed calm: “There were no worried or furrowed brows indicating deep discomfort about this exercise.”

How to react publicly to Zapad is in fact a finely balanced strategic question question. If western Europeans laugh off the exercises as saber-rattling while those in the east are deeply concerned, Gressel said, it plays into Russia’s hands. “That creates a division within the alliance, a sense of divided security,” he says, which Russia is deliberately trying to exploit. On the other hand, getting too worked up about the operation “works to Moscow’s advantage,” says Galeotti. “It takes a substantial but not massive operation and turns it into something far more existentially threatening.”

Could Russia use Zapad to invade the Baltics?

Galeotti and Kupchan both say Russia is very unlikely to invade the Baltics as it did Crimea. Taking on NATO is a very different ball game to battling Ukraine or Georgia, they say, especially since Russia’s professional forces are already thinly spread around Syria and Ukraine.

Gressel also thinks it’s unlikely but cautions that, while invading the Baltics “would be crazy” according to Western logic, “the reality that is that in the Russian intelligence service they don’t think in that logic. They think utterly differently, much more anarchistic, that all rules and norms are for sissies and big powers have the right to make their own rules according to the situation. It is much more about prestige and power status.”

None of the three analysts gave much credence to the idea that the Kremlin would permanently leave troops in Belarus.

What should NATO’s response to Zapad be?

NATO has already taken several steps to warn Russia off. It has sent four multinational battalions to rotate around the Baltics and Poland. Last year NATO members deployed around 30,000 troops in Poland, reportedly (paywall) the allies’ largest eastern European military exercise since the end of the Cold War. Kupchan thinks those measures are enough: “NATO has done what’s necessary to send the signal to Russia that it had better not even think about messing around with NATO members.”

Galeotti and Gressel, however, think there’s no harm in NATO running regular exercises of its own. “This is one of the areas where NATO has fallen behind,” Galeotti says. Gressel points to NATO’s cold-war history of annual maneuvers in Germany to scare off the Soviets from attacking. “We’ve never practiced that in Romania and Bulgaria; all the concepts to defend the Baltics are paper concepts,” he says.

Beyond sending a message of intent to Moscow, such exercises have serious practical benefits: “Everything you haven’t practiced in a real war situation doesn’t work, because virtually every plan forgets something or runs into difficulties that you haven’t come across unless you’ve tried it,” says Gressel, a former official in Austria’s defense ministry. “In my mind, we owe it to our allies in the East to show the Russians that we’re not just talking tough; that if they do some nonsense in the East we’re there and we’re going to catch you.”