On Wednesday, the US Army did something that seemed, and maybe was, dangerously provocative: it paraded soldiers and armored vehicles from the Second Cavalry Regiment in the Estonian town of Narva, just 900 feet from Russia's border.

The Washington Post's Michael Birnbaum, reporting the incident, explains, "Narva is a vulnerable border city separated by a river from Russia. It has often been cited as a potential target for the Kremlin if it wanted to escalate its conflict with the West onto NATO territory."

There is a logic to this sort of demonstration, which is surely meant to show Russia that the US is sincerely committed to the defense of Estonia, which is a member of NATO. In other words, it is meant to deter Russia from starting a Ukraine-style conflict in Estonia, which could plausibly spiral into World War Three. At the same time, such a demonstration is also dangerous, as it risks being misinterpreted by Moscow as an act of aggression and thus making war more likely.

The US is threatening war to make war less likely

Estonia and other Baltic countries, like Ukraine, used to be part of the Soviet Union and have significant Russian or Russian-speaking minorities. Europe has feared that Vladimir Putin might attempt some version of what he did in Ukraine, stirring up pro-Russian sentiment, arming separatists, or even overtly invading. President Obama took this seriously enough to travel to Estonia in September to give a speech pledging that the US would defend the country against Russian aggression.

This isn't just scary because it would be bad to repeat the Ukraine crisis in another country, though it surely would. Estonia is a member of NATO, which means that all other members are committed to help defend it in a war. That includes the US and most European countries, two of which (France and the UK) are nuclear armed. If Putin were to invade Estonia tomorrow, it would spark war between several nuclear powers, and that would be a global catastrophe.

Putin does not want World War Three, though, so he's not going to simply invade Estonia. What's more plausible, and in many ways scarier, is the possibility that he could attempt smaller and more indirect provocations of the sort he deployed at first in Ukraine.

Indeed, shortly after Obama's speech there, a handful of Russian agents crossed the border and kidnapped an Estonian state security officer. It was not an act of overt war, it certainly seemed like a provocation intended to signal Moscow's willingness and desire to bully its Baltic neighbors. It's not difficult to imagine how Putin could follow it up with a more provocative act, then another, then another, until the US felt some sort of uncrossable line had been crossed and felt compelled to respond militarily.

The core danger is not that Russia would deliberately start a war. It's that Russia and the US might have different understandings of where the bar is for what would trigger war. A fear you hear expressed by some analysts is that Russia believes the US has set that bar very high — that Russia could get pretty aggressive with Estonia without an triggering a retaliation — but that the US has in fact set it quite low.

This mismatch in perceptions is really dangerous, because it means Putin could accidentally trigger war by misreading American intentions. Parading a bunch of US Army armored vehicles within sight of the Russian border is meant to to convey to Moscow that the US is so serious about defending Estonia that it would consider Russia stirring up trouble even in this little border town to be a trigger for war.

To be clear, this is distinct from the popular and wrongheaded conservative argument that Obama is emboldening America's enemies by being insufficiently tough or by not bombing enough countries. The concern is not that Obama is weak (if anything, it's the strength of his commitment to deterrence in Estonia that is coming into play). Rather, the concern is that the US and Russia do not have the same understanding of where the US draws the line for war. Obama is trying to make that line as clear as possible to Putin — and prevent it from getting crossed.

If Putin misreads this as an act of aggression, it could make things more dangerous, not less

This only works, though, if Putin sees the US Army parading on his border and understands that it's meant as a deterrent. It's all too possible that Putin, who is known to get a bit paranoid about US intentions, could read this as a threat of American aggression or outright invasion. That would make things substantially more dangerous.

An underlying issue in the Ukraine war is that the Kremlin seems to earnestly believe that the crisis began because the US backed a fascist coup in Kiev (in fact, pro-Europe protesters ousted the pro-Russia president) and that the West is motivated by innate hostility to Russia. The US certainly sees Russia as the aggressor. But if both sides see one another as the hostile aggressor that must be deterred, then any act of escalation invites more escalation, which raises the risk of war.

This gets to part of the problem of the crisis between the US and Russia: their respective leaderships simply live in different realities. Putin, having dismantled much of Russia's free media and replaced it with dogmatic state media, has become the victim of his own propaganda bubble. That makes it more important to deter him from further aggression, but it also means that demonstrations like this week's in Estonia risk being misperceived as something they are not.

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