In the historic heart of Riga, Latvia’s lively capital, there is a building that reveals why the Baltic States remain so wary of the Russian Bear. From the street, it doesn’t look like much – just another apartment block on a busy boulevard full of shops and cafes. Only the discreet sign outside gives the game away: ‘During the Soviet occupation the KGB imprisoned, tortured, killed and morally humiliated its victims in this building.’ Most passers-by barely give it a second glance. They know this story all too well.

The KGB vacated this apartment block in 1991 when Latvia regained her independence, but over 30 years later the memories remain raw. As we step inside my Latvian guide, Edgars, tells me his father was summoned here twice for interrogation. Thankfully these enquiries went no further, but other Latvians weren’t so lucky. During the first Soviet occupation, from 1940 to 1941, nearly 200 dissidents were executed in this building. During the second Soviet occupation, from 1944 to 1991, 48,000 Latvians were investigated for all sorts of ‘anti-Soviet offences’ here. Some, like Edgars’ father, were released – eventually. Many were sent to Siberia. Some simply disappeared.

We are shown the interrogation room, the execution room, and the cells in the basement down below. Yet the most disturbing feature is the letterbox in the foyer. Here Latvians could post letters accusing their neighbours of ‘counter-revolutionary activity’. Definitions of such activities were suitably vague. ‘A counter-revolutionary action is any action aimed at overthrowing, undermining or weakening the power of workers’ and peasants’ Soviets,’ declared Article 58 of the Soviet Criminal Code. Offences included cracking subversive jokes and listening to western radio.

The last time I visited this ‘House on the Corner’ (as Latvians used to call it, euphemistically), Russia had just invaded Crimea and Latvians were aghast. This building was a sinister relic of a dark era that Latvians assumed was now behind them. Russia’s invasion of Crimea made it horribly topical again. After a brief flirtation with the West, was Russia now set upon a new path: to restore the old boundaries of the USSR, boundaries that included Lithuania, Latvia and Estonia, aka the Baltic States?

For westerners, Russia’s invasion of mainland Ukraine was the big wake-up call, but for inhabitants of the Baltic States it was simply more of the same. Nato membership gives these three countries the sort of protection Ukrainians can only dream of, yet for these former Soviet republics, the war in Ukraine still feels especially close to home.

I’d visited Latvia and Estonia a few times since Russia invaded Crimea, but I hadn’t been back since Russia invaded mainland Ukraine. So when I was invited to join a small press tour of former military sites in Latvia and Estonia (alongside two Dutch journalists, and a Dane), I needed no persuading. It seemed like an ideal opportunity to gauge how the mood in the Baltic States had changed.

The Estonian-Latvian military heritage trail is an enormous network of 173 sites spread across both countries – barracks, bunkers, fortifications – dating from the dying days of Tsarist Russia to the dying days of the USSR. You’d need several months to see them all, but even visiting a small selection gives you an intimate insight into the troubled history of this region, at a time when those historic conflicts no longer feel confined to the distant past.

That Latvia and Estonia are working on this project together makes good sense; although these two countries are quite distinct their recent histories run in tandem. Colonised by Tsarist Russia, they became independent after the Russian Revolution, only to be swallowed up again by Russia at the start of the second world war. In 1941 the Nazis drove the Russians out and installed a tyranny of their own; in 1944 the Red Army drove the Nazis out and subsumed both countries (along with Lithuania) into the USSR. For half a century Latvia and Estonia vanished from the map of Europe, finally re-emerging as independent states (alongside Lithuania) after the collapse of the USSR. Yet the Soviet occupation still feels like recent news. Anyone over 40 has clear memories of the occupation. They all have tales to tell.

With 200,000 Soviet troops stationed in a country with a population of barely two million, Latvia was one of the most heavily militarised republics in the USSR and Estonia wasn’t far behind. When those Soviet troops withdrew, they left behind a vast array of military installations. These ghostly relics of the Cold War constitute a warning from history – a timely reminder of Russia’s longstanding involvement in this region.

This contested history is epitomised by the recent dispute over Riga’s so-called Victory Monument. Erected by the USSR, this ‘Monument to the Liberators of Soviet Latvia & Riga from German Fascist Invaders’ (to give it its full title) has been a focus of fierce controversy since Latvia regained her independence. For the communists who built it, this was a tribute to the soldiers who defeated Hitler. However for many Latvians, this is not just a war memorial, but a monument to Stalin’s conquest and colonisation of Latvia.

Latvia has a large Russian-speaking minority, about a quarter of the population. Brought here by the Soviets, at a time when many Latvians were deported to other parts of the Soviet Union, many of these Russian speakers retain close cultural connections with Russia. Among some members of this community, plans to dismantle the Victory Monument have provoked strident opposition. However, Russia’s invasion of Ukraine has tipped the balance, seemingly irrevocably. In May, the Latvian parliament resolved to remove this monument. Today it’s fenced off, awaiting demolition.

We drove to Mangalsala, at the mouth of the Daugava River. This is the maritime entry to Riga, an important port since the Middle Ages, and so it used to be heavily fortified. Not anymore. A forest has grown up around these battlements, and it’s quite a task to find them. The guns themselves are long gone, but the concrete bunkers that guarded them remain. Most of them are Soviet, but some are German, Latvian, even Tsarist; artillery emplacements, built to repel invading navies, from east and west.

Wandering around these woods, you realise how many layers there are to Latvian history. A Soviet memorial, half hidden in the trees, commemorates the Latvians who died fighting for the insurgents in the abortive Russian Revolution of 1905. Back in Riga that evening, we drove past the Soviet memorial to the Red Latvian Riflemen, Latvian soldiers who deserted the Tsar’s army to fight for Lenin in the revolution of 1917. Half a century of Soviet rule cured Latvia of its Bolshevik sympathies, but it would be disingenuous to pretend it isn’t an important part of the country’s past.

Next day we drove way out west, towards the Baltic Coast, stopping off en route at a bunker of the Forest Brothers – another forgotten episode in the history of this region. The Forest Brothers is the common name given to Latvian, Estonian and Lithuanian partisans, who conducted a vigorous guerrilla campaign against foreign invaders: against the Red Army in 1940, against the Nazis from 1941 to 1944, and then against the Red Army again from 1945. At the end of the second world war, they hoped the Allies would restore their independence. Instead, they were swallowed up by Stalin. Undeterred, they kept on fighting until the mid-1950s. During the Soviet occupation, it was impossible to commemorate this resistance movement. By preserving these rudimentary bunkers, the descendants of these freedom fighters are reclaiming a forbidden chapter of their history.

We drove on and on, through endless forest, into one of the wildest parts of Latvia. Our destination was the Ventspils International Radio Astronomy Centre, a colossal radio telescope over 100ft in diameter, one of the biggest in the world. Today it’s used for stargazing, but during the Cold War it was used to eavesdrop on Nato. Cloaked in secrecy throughout the Cold War, the entire area was off-limits. Its clandestine function only became apparent when Russian troops left in 1993. Some of the surrounding barracks have been demolished, others have simply been abandoned. One of the surviving buildings houses a makeshift museum. There’s the usual collection of Soviet paraphernalia, but the mementoes that really caught my eye were the snapshots of young soldiers, smiling for the camera. Was this the worst of times for these youngsters or the best of times? I couldn’t tell.

On our third day, we drove east, towards Estonia, stopping off at the secret Soviet bunker in Ligatne – 2000 sq metres of offices and dormitories, buried nine metres underground. Built to withstand a nuclear attack and its radioactive aftermath, it was intended to accommodate 250 key communist functionaries, living for three months below ground. It felt strange and rather spooky tramping around this subterranean labyrinth, surveying the antiquated equipment and Soviet bric-a-brac that the Russians had left behind.

However, for me, the most memorable aspect of our underground tour was our guide, Nadiya, a Ukrainian refugee. She personified the close connection between these Cold War sites and Russia’s new war in Ukraine. Talking to her, it’s clear that, this bunker is more than a mere tourist attraction. ‘For myself, it’s a reminder about those times – not to forget how it was years ago,’ she tells me. ‘To be aware of those times, and to be ready to protect yourself in case there is an attempt to resume such a regime.’

On our last day, we caught the ferry to Hiiumaa, one of Estonia’s largest islands. Our Estonian guide, Ain, met us off the boat. A native of Hiiumaa, he’s assembled his own military museum in an old Soviet base in the forest. It’s full of military hardware, salvaged from all around the island.

Ain took us on a tour of the island’s coastal batteries. Like much of the Estonian coastline, these sites were strictly out of bounds for locals. ‘You were not allowed to go to sea – you were not even allowed to go to the coast,’ says Ain. The watchtowers along the shore weren’t just there to look out for enemy shipping. They were also there to look out for Estonians trying to escape to the West across the water. Now nature has reclaimed this landscape. The trees are taking over. Barely 30 years later, there isn’t much left to see.

In the lobby of our hotel, I found a copy of the local newspaper. The front page showed a Red Army tank being lifted onto a transporter. A Soviet war memorial in Narva, the easternmost town in Estonia, hard up against the Russian border, it was being removed, bound for a military museum. Similar monuments here in Hiiumaa seem destined for the same fate. Ain shows us a local war memorial, dedicated to the soldiers of the Red Army. ‘For the people who have fallen for the freedom of our homeland,’ he reads, translating from the Russian. ‘But “our homeland” meant their homeland,’ he adds, emphatically. ‘For us they were an occupying power.’

Ain hopes to preserve this war memorial, and others like it, in his military museum. He thinks that’s the best place for them, and I agree. They’re part of the history of the Baltic States, and they shouldn’t be forgotten, but nor should they be venerated. ‘We are not making propaganda – we are collecting and showing information,’ he says. For me, this phrase seemed to sum up the entire trip. There’s nothing didactic about these military sites. The Latvians and Estonians aren’t making propaganda. They’re simply showing the world what happened here, something they were never allowed to do during the Soviet occupation. Visitors are free to draw their own conclusions and the conclusion I drew from this brief visit was that peace and freedom are precarious – especially here – and so easily forsaken.

‘You were punished as a criminal if you raised our national flag,’ says Ain. ‘We wanted to become free. This became true, and the rest has been in our hands.’ But just because those bad old days are over, that doesn’t mean the Cold War is done and dusted, or that the USSR is ancient history. That was what we in the West liked to tell ourselves these last 30 years, but the Russian invasion of Ukraine changed everything. The difference between western Europe and the Baltic states is that the Baltic states didn’t need to wait until Russia invaded mainland Ukraine. They knew things had changed back in 2014 when Russia invaded Crimea.

As I flew out of Hiiumaa the next morning, on a small propeller plane bound for Tallinn, I recalled something Nadiya, our Ukrainian guide, had said as she showed us around that secret bunker in Ligatne, where Latvia’s Soviet bigwigs planned to hunker down after the outbreak of a nuclear war. ‘There was only one country – the Soviet Union. The rest were republics – socialist republics.’ The former socialist republics of Latvia and Estonia understand how fragile liberty can be. But do we?