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Estonia is one of the countries in Eastern Europe where US tanks, artillery and other military equipment will soon start arriving, Defense Secretary Ash Carter said on Tuesday in the Estonian capital, Tallinn. But there is one community in Estonia that may have mixed feelings about these new US deployments.

Nato has a Russian city. It's called Narva and its main feature is a 12th Century castle overlooking the Narva River. Climb to the top and you can peer down on its ancient nemesis - the fortress of Ivangorod that sprawls along the opposite bank. This spot has long been a place of conflict between east and west. Today, Ivangorod and its fortress are in Russia. Narva and its castle are in Estonia, which means they're in the EU and Nato.

But Narva's people are almost entirely - and often resolutely - Russian.

Image caption The view of Ivangorod from the Estonian side of the border

Note the Russian television on in seemingly every home, lobby and restaurant. Note the statue of Lenin on the castle grounds. And the Soviet tank on a stone plinth by the river. And the crowd laying flowers by it on Victory Day - when Russians everywhere celebrate the Nazi defeat in 1945.

A concert on that day last month featured a lot of flags. There were Russian ones, with white, blue and red bars. And Soviet ones, with a golden hammer, sickle and star set against a bright red banner. But there was not one blue, black and white Estonian flag.

"They have their own traditions," one man told me.

I even saw a flag used by the Russian rebels in the Ukrainian city of Donetsk. Donetsk is a sister city to Narva. The guy with its flag said its people need support - "they're being bombed right now".

Narva in numbers

Third largest city in Estonia - population of 58,000

Ethnic Russians make up 83% of the population, ethnic Estonians make up 4%

More than 36% of the population has Russian citizenship, 47% has Estonian citizenship

Source: Narva municipality

Could what's happening in Donetsk happen here, I asked.

"It's very much possible," he said. "Estonia is somewhere out there," gesturing west. "We're on our own. The government only remembers us before election days."

There's a history here. To liberate Narva the Soviets bombed it flat. They then moved in tens of thousands of Russian civilians. To build - or as many Estonians see it - to occupy. Estonia only regained independence in 1991 with the collapse of communism. It has since had a sometimes awkward relationship with its Russians, who make up a quarter of the total population. Some don't have equal citizenship or voting rights. The president once told the BBC there's no more reason to speak Russian in Estonia than Japanese or Urdu. For him to even speak Russian, he said, would legitimise 50 years of Soviet brutalisation.

So Russians don't always feel the warm embrace of the Estonian state. And it's not as if they're so busy getting rich they don't notice. Narva has seen better days. The giant factories that once employed so many sit empty. Plants grow out of the bricks. An affable middle-aged man named Slava Konovalov helped me slip into an abandoned textile mill where his mother used to work. He remembers the deafening noise of the place when he came to see her as a boy. Now, the only sounds were our voices echoing around a vast courtyard, the crunch of rubble beneath our feet and the caw of a lone ornery crow.

Image caption An abandoned textile mill in Narva

Slava's mum was one of those Russians who moved here after the war. When she got her first paycheck she thought there was a mistake. She was earning three times as much as she did back home in Russia. It was no mistake. Narva, Slava said, was a good place to be Russian. Today, that's less true. Russians in Estonia are still doing better economically than Russians in Russia. But compared to their countrymen in Estonia, they're doing worse. Slava, a local official with figures to hand, says people in Narva on average earn a third less than Estonians in general.

Local grievances can add up and the Estonian government believes the Kremlin is already trying to use them to undermine the state. This is obvious, the government communications director, Ilmar Raag, told me. Russian television is hostile, he said, fabricating stories and exaggerating problems. He doesn't believe it has yet created a fifth column eager to rise up and break away, as in Ukraine. But there are unnerving signs.

He asked young people in Narva who their leader was. Their answer? Vladimir Putin.

"If Putin would say to this population - you should do something hostile - then no-one knows what will happen," Raag said.

Image caption Estonia recently held its largest-ever war gaming exercise

For his part, Putin throws his hands up at such talk. He told an interviewer earlier this month, "Only an insane person and only in a dream can imagine that Russia would suddenly attack Nato."

The Estonians are not betting on his sanity. They recently held their largest-ever war games and are one of the few countries to meet its Nato commitment to spend 2% of GDP on defence. They've also launched a campaign to bolster what they call the country's "psychological defences" against Russian misinformation. It includes civics classes in schools and a new Russian-language TV station... with a studio in Narva.

The campaign's success will be measured over years. Meanwhile, if Putin does want to cause trouble inside Nato, he's got material to work with.

Listen to Neal Razzell's radio documentary, Estonia's Russian Problem, on Assignment, on the BBC World Service. You can find transmission times on the same page.

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