Captain Markus Aarnio, chief of the Gulf of Finland naval command, has the sort of craggy good looks associated with the hero of a cold war movie. Standing stiffly in a control centre overlooking Helsinki harbour against a backdrop of grey seas and driving sleet, he appears poised to dash off at any moment for a real-life remake of the Sean Connery film The Hunt for Red October.

Aarnio’s job, along with those of other members of Finland’s army, navy and air force, border guard and coastguard, and a good chunk of the national political, academic and media establishment, can be summed up in three words: watching the Russians.

Russia-watching has become a national obsession since Finland broke free of the Russian empire in 1917. Two bitterly fought wars with the Soviet Union during the second world war are far from forgotten. Neither are the tense years of the cold war, when Finland pursued a delicate balancing act between the importunate demands of its giant neighbour and its natural attachment to the west.

After the Berlin wall came down in 1989 and political chaos followed the Soviet Union’s implosion, Finland’s 840-mile land border with Russia and its territorial waters still required guarding, though for different reasons.

Now – with a newly expansionist, jingoistic Russia led by President Vladimir Putin set on reasserting itself internationally, with eastern Europe and the Baltic states wondering fearfully what may follow its armed intervention in eastern Ukraine, and with close military encounters between Russia and the west running at cold war levels – Finland is once again on red alert.

Aarnio’s area of operations commands the highly congested approaches to St Petersburg and the oil export terminals crucial to Russia’s economic survival. Each year, 43,000 ships and tankers travel along an often ice-bound, six-mile-wide international corridor leading from Russian waters to the wider Baltic and thence to the Atlantic. And those are the ones Aarnio knows about. As the recent, abortive Swedish hunt for a suspected Russian submarine suggested, not everything Moscow sets afloat may be visible.

“Our work includes maritime surveillance and ship recognition. We maintain 24-hour vigilance,” Aarnio said. His command includes missile boats, a mine warfare squadron, a coastal battalion and special forces, including divers.

A photograph of a Russian AN-72 transport plane taken by a Finnish pilot in August. Photograph: Associated Press

Although Russian military activity is up in the past six months, there have been no maritime incidents comparable to three apparently concerted violations of Finnish airspace in August by Russian aircraft, which caused widespread consternation about Moscow’s intentions. “Right now we do not have any trouble with the Russians,” Aarnio said. Judging by the grim look on his face, the Russians may do well to keep it that way.

Alexander Stubb, Finland’s boyish-looking conservative prime minister, agreed on the need to keep things calm. Finland had good bilateral relations with Russia, he said, but it was important western countries understood what they were dealing with.

“The situation is naturally worrying from a European and Finnish perspective. I said in 2008 after the war in Georgia that power politics, spheres of influence and war had returned to the borders of Europe. I hoped I was wrong. Now, unfortunately, we are back to square one. There’s a lot of cold war rhetoric,” Stubb said.

“I think Russia has made two strategic mistakes. Number one is the destabilisation of its neighbourhood, in particular annexing Crimea … I want stable not unstable borders. The second is they still rely on fossil fuels for economic growth, and that is an impediment to modernising their economy.

“We in the west need to reassess our relations with Russia … We have put in a lot of effort to try to integrate Russia into western institutions and we slightly idealistically believed that Russia could become a normal, liberal market democracy that relies on international institutions. It hasn’t. So we have to be both pragmatic and principled.”

In part, that meant strong Finnish support for American and EU sanctions on Russia, even though they were hurting Finland’s economy, Stubb said.

Cpt Markus Aarnio says the Finnih navy is alert 24 hours a day to the potential dangers posed by Russia. Photograph: Markus Artturi Aarnio

Jaakko Iloniemi, Finland’s former ambassador to the US, said the outlines of the problem were clear. “Their military and naval activity is certainly up. For Putin it’s about showing the flag and restoring pride. The Russians call it [the Crimea operation] ‘fast power’ – there are no democratic encumbrances, executive power is sovereign, the legislature, the military, the media, the judiciary are compliant. Putin’s achilles heel is the economy … So he needs external crises and foreign devils,” Iloniemi said.

René Nyberg, a former ambassador to Russia, said Finland and the west were facing a new situation and it was uncertain where it might lead. Putin did not have a clear plan in Ukraine or elsewhere but had acted opportunistically in reaction to events, he said.

“Fast power became hasty power,” Nyberg said. “The possible loss of Ukraine was seen by Russia as an existential threat. It wasn’t really. But it challenged Moscow like nothing else. It was projected as a Nato-US-international conspiracy.”

The Ukraine crisis had cost Russia far more than it anticipated in terms of forfeited investment, devaluation of the rouble, lost trade and higher prices caused by sanctions, said Nyberg. A falling oil price was also causing serious economic damage. Ironically, with relations with the US at a low point, and China interested in Russia only for cheap energy and raw materials, Moscow needed the EU more than ever.

“The economy is getting worse, the oil price is killing them. Russia needs Europe but these are the very people they are alienating,” Nyberg said.

A senior government insider said Finland backed the EU stance but was concerned about what might happen if Russia’s internal situation deteriorated.

“Russia’s actions in Ukraine are more a show of weakness and fear. This is not expansionism, this is insecurity,” the insider said. “Nevertheless we need to send a signal that we are not soft targets or else Ukraine could happen again elsewhere … You cannot rule it out [but] Russian intervention in the Baltic states is unlikely. It would be much harder for them there than in Crimea. People in the Baltics know they have a better life than those in Russia and inter-ethnic relations are relatively good.

“The bigger point is that the Russian economy is living on borrowed time. There is genuine concern, especially in Germany, that their oil and gas industry is so inefficient that they eventually will be unable to deliver. If they get very desperate, we don’t know what they would do.

“In the near term, Russia will continue to try to bully and threaten us. The EU is in disarray, physically and mentally. But in five to 10 years it will be different … When it comes, it [a Russian collapse] could be like a stock market panic. Putin is no Gorbachev, he is not a guy who is going to give up. He will not go quietly. Remember, this is a global nuclear power we are talking about,” the insider said.

Opinions differ about how Finland should handle the Russian challenge. The country is deeply split, as ever, over the question of Nato membership, with about 60% of voters opposed.

But there is also concern about a return to the bad old cold war days of “Finlandisation”, when Finnish governments sometimes appeared too eager to appease the Soviet leadership at the expense of their country’s values and independence. Some Finns believe this may already be happening. As Lasse Lehtinen, a retired MP and newspapercolumnist, put it, Finlandisation is creeping back.

Practical considerations also apply. Finland, lacking fossil fuel deposits, is also highly dependent on Russian energy imports – 71% of its oil, 66% of its coal and 100% of its gas comes from Russia. In other areas, too, Russia is a major trade partner and export market. Meanwhile, Finland’s own economy is struggling. Controversially, the defence budget is facing a sharp 10% cut. To compensate, closer military integration with Sweden, another non-Nato state, is planned.

Russian corvette Boikiy is pictured from the deck of Finnish research vessel Aranda in international waters in September. Lehtikuva/Reuters Photograph: Lehtikuva/Reuters

Erkki Tuomioja, a lifelong social democrat and foreign minister in Stubb’s ruling coalition, said Finland supported sanctions on Russia over Ukraine. But he was critical of the EU’s handling of relations with the Kiev government.

“The EU made a mistake last year concerning the association agreement with Ukraine in not talking first to the Russians, at least to set their wildest fears at rest,” he said. Europe’s biggest states had failed to give the EU a clear mandate to deal with the crisis. US leadership had also been found wanting.

Tuomioja, who opposes Nato membership, said he did not believe Putin had a grand design for restoring Russian greatness. “I think it’s more an ideal or wishful thinking … Russia overall is going backwards now. The west mismanaged relations in the 1990s but we don’t know whether [what is happening now] could have been avoided.”

More exchanges with Russia’s leadership and ordinary Russians were needed at every level to avoid making the same mistakes in future, he said.

Yet whatever happened, the government insider insisted, Finland would not kowtow to Moscow. “There is zero appetite for going back to the old way of doing things, to placating and appeasing Russia. We’re not looking for a fight. But we need to be able to deal with Russia. Russia is our everyday reality.”