Russia's next move? The countries trying to Putin-proof themselves

"I ed the air force 35 years ago, aged 18, and went straight to , based on a Tornado aircraft," says British Air Commodore Andy Turk, who is now deputy commander of the Nato Airborne Early Warning & Control Force (AWACS). "It was towards the end of the Cold War and we had a nuclear role back then.

"After the War, we hoped for a peace dividend, to move on geopolitically, but clearly that's not something Russia wants to do. And now my eldest son is banging on the door to the air force, wanting to make a difference too... It does feel a little circular."

We are around 30,000 feet above the Baltic Sea, on a Nato surveillance plane equipped with a giant, shiny, mushroom-resembling radar, enabling crew to scan the region for hundreds of miles around, looking for suspicious Russian activity.

Air policing missions like this - and Nato hip more broadly - have long made tiny Baltic nations of Lithuania, Latvia and Estonia (which neighbour Russia) feel safe. But US President Donald Trump is changing that, thanks to his affinity with Vladimir Putin, which has been evident since his first term in office.

Trump has been very clear with Europe that, for the first time since World War Two, the continent can no longer take US military for granted.

That leaves the Baltics nervously biting their nails. They spent 40 years swallowed up by the Soviet Union until it broke apart at the end of the Cold War.

They are now of both the EU and Nato, but Putin still openly believes the Baltics belong back in Russia's sphere of influence.

And if the Russian president is victorious in Ukraine, might he then turn his attention towards them - particularly if he senses that Trump might not feel moved to intervene on their behalf?

Ian Bond, deputy director of the Centre for European Reform, thinks that if a long-term ceasefire is eventually agreed in Ukraine, Putin would be unlikely to stop there.

"Nobody in their right mind wants to think that a European war is around the corner again. But the reality is an increasing number of European intelligence officials have been telling us that…

"Whether this is coming in three years or five years or ten years, what they are saying is the idea that peace in Europe is going to last forever is now a thing of the past."

Russia's economy is currently on a war footing. Roughly 40% of its federal budget is being spent on defence and internal security.

More and more of the economy is being devoted to producing materials for war.

"We can see what the Russian economy is being retooled to do," observes Mr Bond, "and it ain't peace."

When you travel to windswept Narva, in northern Estonia, you see why the country feels so exposed.

Russia borders Estonia, all the way from north to south. Narva is separated from Russia by a river with the same name. A medieval looking fortress straddles each bank – one flying the Russian flag and the other, the Estonian. In between is a bridge – one of Europe's last pedestrian crossings still open to Russia.

"We are used to their tricks and their tactics," Estonian Border Police Chief Egert Belitsev told me.

"The Russian threat is nothing new for us." Right now, he says, "there are constant provocations and tensions" on the border.

The border police have recorded thermal imaging of buoys in the Narva River that demarcate the border between the two countries being removed by Russian guards under the cover of darkness.

"We use aerial devices – drones, helicopters, and aircraft, all of which use a GPS signal – and there is constant GPS jamming going on. So Russia is having huge consequences on how we are able to carry out our tasks."

Later on, keeping to the Estonian side, I walked along the snow-covered bridge crossing towards the Russian side and watched the Russian border guard watching me, watching him. We were just metres away from each other.

Last year, Estonia furnished the bridge with dragon's teeth – pyramidal anti-tank obstacles of reinforced concrete.

I've not heard anyone suggest Russia would send tonnes of tanks over. It doesn't need to. Even a few troops could cause great instability.

Some 96% of people in Narva are mother-tongue Russian speakers. Many have dual citizenship.

Estonia worries a confident Vladimir Putin might use the big ethnic Russian community in and around Narva as an excuse to invade. It's a playbook he's used before in Georgia as well as Ukraine.

In a dramatic indication of the growing anxiety, Estonia, alongside Lithuania and Poland, tly announced this week that they're asking their respective parliaments to approve a withdrawal from the international anti-personnel mines' treaty which prohibits the use of those mines, signed by 160 countries worldwide.

This was to allow them "greater flexibility" in defending their borders, they said. Lithuania had already withdrawn from an international convention banning cluster bombs earlier this month.

Camille Grand of the European Council on Foreign Relations, who is the former Assistant Secretary General for Defence Investment at Nato, thinks that post-Ukraine, Putin would be more likely to target a non-Nato country (such as Moldova) rather than provoke a Nato nation – because of the lower risk of international backlash.

Estonia and the other Baltic nations were traditionally more vulnerable than the rest of Nato, as they were geographically isolated from the alliance's in western Europe, according to Mr Grand. But that has been largely resolved now, since Sweden and Finland ed Nato, following Russia's full-scale invasion of Ukraine.

"The Baltic Sea has become the Nato Sea," he notes.

Dr Marion Messmer, a senior research fellow on the International Security Programme at Chatham House, thinks the most likely trigger for a war with Russia would be miscalculation, rather than design.

If peace is agreed in Ukraine, Dr Messmer predicts that Russia will probably continue with misinformation campaigns and cyber warfare in Europe, as well as sabotage and espionage in the Baltic Sea. "I think they are likely to continue with any kind of destabilising activity, even if we are to see a peace that's positive for Ukraine."

Dr Messmer continues: "One of the risks I see is that essentially an accident could happen in the Baltic Sea that's completely inadvertent, but that's essentially a result of either Russian grey zone activity or Russian brinkmanship where they thought they had control of a situation and it turns out they didn't. That then turns into a confrontation between a Nato member state and Russia that could spiral into something else."

But Mr Grand was keen not to totally downplay the risk of Putin targeting the Baltics.

Presumably, the Russian president would first mull how likely Nato allies would be to retaliate.

Would the US, or even , Italy or the UK, risk going to war with nuclear power Russia over Narva, a small part of tiny Estonia, on the eastern fringe of Nato?

And suppose we were to see a repeat of what happened in the Donbas in eastern Ukraine in 2014 when Russian paramilitaries engaged in fighting did not identify as Russian soldiers? This allows Putin plausible deniability - and in those circumstances, would Nato wade-in to help Estonia?

If they didn't, the advantages for Putin might be tempting. The unity principle of the western military alliance he loathes would be undermined.

He'd also destabilise the wider Baltics, probably socially, politically, and economically, as a Russian incursion – however limited – would likely put off foreign investors viewing this as a stable region.

Another concern that has been discussed in Estonia is that Donald Trump could end up pulling out, or significantly reducing, the number of troops and military capabilities the US has long stationed in Europe.

Estonian Defence Minister Hanno Pevkur put a brave face on things when I met him in the capital Tallinn: "Regarding (US) presence, we don't know what the decision of the American istration is.

"They have said very clearly they will focus more on the Pacific and they've said clearly Europe has to take more responsibility for Europe. We agree on that.

"We have to believe in ourselves and to trust our allies, also Americans… I'm quite confident that attacking just even a piece of Estonia, this is the attack against (all of) Nato."

"And this is the question then to all the allies, to all 32 ," Pevkur adds. "Are we together or not"Getty Images Donald Tusk, Poland's prime minister " class="sc-d1200759-0 dvfjxj"/>Getty Images