Russia's invasion of Ukraine caught many by surprise. But the effects will be long-term, both for Ukraine and the wider world. And against a backdrop of superpower tension, there are renewed fears of nuclear conflict - and few ideas about how the current situation will end.

openDemocracy spoke to Cold War historian Sergey Radchenko to understand what led to Russia's invasion of Ukraine, whether we are returning to a Cold War, and what scenarios he envisions for the future.

Russia's invasion of Ukraine seems to have surprised pretty much everyone and has been described as mad. What do you think led to it?

This invasion was an obvious miscalculation on the part of Putin. People have said that Putin is unhinged, that he's deranged, that he just wanted to annex Ukraine. Actually, even if he wanted to annex Ukraine, which is not clear, his actions can be explained in terms of the rational actor theory.

That is to say, Putin did not expect this sort of reaction from the West. He did expect certain sanctions, there's no doubt about that. But the Russian policy community in general and I think Putin in particular were quite surprised by the solidarity that this war triggered in the West. The sanctions that were applied are probably unprecedented as far as Russia is concerned. So he miscalculated.

Another area where Putin miscalculated was that he thought the Ukrainian reaction would be quite weak. Ukraine was, he believed, in a state of semi-collapse and therefore Russian troops would be welcome. Yet what he encountered was resistance that brought together large segments of the Ukrainian population. Even those people who were not necessarily on the best of terms prior to the Russian invasion have been brought together by this national emergency.

But where he calculated correctly so far is that he thought that there would not be much of a Western response in terms of direct confrontation with Russia. Because there was an assumption in his mind - an assumption that still needs to be proven wrong - that Ukraine was not covered by Article 5 of the NATO Treaty. Ukraine is not part of NATO. So it's like the West already gave up on Ukraine ahead of time.

In other words, Ukraine was left to its own devices and Putin thought that under those circumstances he could get away with launching this war. If you look carefully, you can see that these are all rational calculations. But he miscalculated, so this is where we find ourselves.

Why did the peace talks that preceded this full-scale invasion stall?

What Russia wanted ahead of this invasion of Ukraine was for Kyiv to implement the Minsk agreements. That plan would have included changing the Ukrainian constitution and recognising that Donetsk and Luhansk are autonomous, introducing a special provision to this effect in the Constitution. The other thing that Moscow wanted was to make sure that Ukraine would never be admitted to NATO.

Now that Russia has invaded, the stakes have gone up significantly. Their bottom line is now considerably worse from the perspective of Ukraine than prior to the invasion. Now the Russians want Ukraine to recognise the independence of Luhansk and Donetsk, presumably in their current borders, which are larger than their previous borders, and recognition of Crimea, in addition to Ukraine vouching that it will not be joining NATO. Those are extremely high demands that the Ukrainian government will find really difficult to accept, especially now that Russia is invading their country.

The outcome for now, despite the fact that some countries are trying to mediate - Turkey is one, China is another - is that the two sides appear so far apart and the stakes are so high. For Putin to back down now and to accept defeat would be very difficult politically. He's quite likely to persist and turn Ukraine into a bloodbath on his way to securing an acceptable victory for himself.

Could more have been done to implement the Minsk agreements?

In retrospect, I do wonder what could have been done to address Russia's so-called security concerns, whether we think those security concerns are justified or not.

Here is why. NATO made it very clear before the Russian invasion actually happened that it would not fight for Ukraine. At present NATO finds itself in a morally questionable position. Civilians are dying in Ukraine and the Ukrainian leadership has spoken time and again about the importance and the necessity of establishing a no-fly zone over Ukraine. Now, this no-fly zone would obviously be a NATO no-fly zone and NATO would thus find itself in open conflict with Russia, which NATO finds unacceptable. But this is the situation.

Why didn't Western countries do more in the run-up to this conflict to facilitate some sort of diplomatic solution with Russia? To give Russia so-called "assurances" of NATO non-enlargement towards Ukraine? It seems that this would have been the morally right thing to do. But of course at the time it was seen as selling out to an aggressor, promoting another Munich. So here we are, several weeks later, Ukraine is a bloodbath. We cannot, of course, blame Ukraine, nor the West. Russia is the one invading Ukraine. You cannot escape this basic fact.

But in terms of chances, opportunities lost, the failure of diplomacy in the run up to the invasion of Ukraine suggests that not enough was done by both sides. Both sides were involved in this "credibility game". And it seems that in the end Putin felt that he had to act because his credibility was involved. So we end up in this bloodbath, which Putin is committing. We should condemn Russia. There is no question about that. But if you reflect back to what happened, I tend to think not enough was done on the diplomatic front.

Is this the start of a new chapter in the Cold War?

This is where a lot of academics will say: this is not a Cold War. In their mind the Cold War involves an existential struggle between communism and capitalism. There's a general consensus among historians that this ideological element was extremely important during the Cold War. Without that element, the Cold War is not the Cold War, they argue.

In my view, it's not so simple. I don't think the ideological element was the most defining element. The key element was, obviously, the existence of nuclear weapons, which made direct confrontation between great powers impossible to contemplate. Therefore, the Cold War was fought out in proxy theatres, whether it was in Vietnam or Afghanistan, or in Africa, or in America.

Today we still have great power confrontation, although of course, the bipolar world of the early Cold War is no longer there. There are many actors here, many power centres. However, there are still nuclear weapons, which make direct conflict between Russia and the United States impossible to contemplate, which is why we're not seeing NATO establishing a no-fly zone over Ukraine, because the cost of nuclear escalation would be too high.

There is, therefore, a continuity between the Cold War of the past and the current period. I don't know if we can say that the period from 1989 to the present was some kind of an interlude. We are not in a position to discuss what the current period should be called. At the moment, we're not even in a cold war, we're in an actual hot war.

There are various ways that the current situation can go. But there's a strong potential for Russia to become even more isolated and to isolate itself, by cutting off sources of Western information, by cutting off contact and by increasing repression on the domestic front. All of this will unfold in the coming weeks and months. Unless there's some kind of a revolution in Moscow, which I do not anticipate at this point. The prognosis is not very promising.

How important is the famous "not one inch East" promise over NATO enlargement? That assurance, made by US Secretary of State James Baker to the Soviets, including Soviet leader Mikhail Gorbachev, in 1990 during German reunification, has featured prominently in discussions over Russia's policy towards Ukraine.

This is where it becomes tricky. There's a general consensus among historians that some assurances were made to the Soviets, and later the Russians, regarding NATO's non-enlargement.

Now I would not say that a deal was struck, although certain assurances were made. When Putin says "we were duped" and that promises were broken, I don't know that he has the grounds to say that. Perhaps if the Soviets or the Russians made different choices in terms of their foreign policy on the basis of this promise, then in retrospect you could say: "we were promised, and then promises were broken, therefore, it seems that we were cheated".

In this case, Gorbachev did not ultimately agree to German reunification and Germany's participation in NATO because he was promised that there would be no major NATO enlargement. Gorbachev did it because he had no other choice: Germany was already reunifying itself and was slipping out of Soviet control. What could the Soviets do to prevent this? Of course, at the time they had military forces in East Germany, but nobody was thinking of using them. And so for that reason, I am not sure that this Russian complaint narrative really has much standing.

It is important to acknowledge that, yes, certain promises were made. We might also say that in the 1990s an opportunity was missed by the West to do more to integrate Russia. That is, to define some sort of institutional role for Russia in structures that actually matter, whether NATO or the European Union. But I think that Russia and Russians themselves should shoulder the greatest part of responsibility for having failed their transition from communism.

Should we be concerned about escalation, particularly against a nuclear power?

Yes, I'm worried about this. As a historian of the Cold War, I'm aware that during the Cold War, we came very close several times to accidental nuclear war. There were moments of tension that could have inadvertently led to nuclear escalation. For example, when it comes to the 1962 Cuban missile crisis, what we know in retrospect was that the main danger came from the actors not having full information about the intention of the other side. By the same token, during the 1983 Able Archer crisis, the Soviets were sure that the Americans were planning a nuclear first strike. We know today that they weren't.

That's why I am worried about the current situation. Although neither side is showing much interest in having a suicidal nuclear war, it could happen as a result of escalation, with people making decisions in the heat of battle that they would not have otherwise made.

What scenarios do you envision for the future?

The current scenario is that there's going to be a negotiated solution to this. Conflicts like this tend to end up as frozen, with neither side actually winning or losing completely.

This is bad news for Ukraine, because Ukraine may lose more territory to Russia or some kind of further unrecognised "republic". Who knows.

It's also bad news for Russia. At the moment we cannot see a trajectory that allows Russia to undo the economic damage that is a result of Western sanctions. As a result of the sanctions, the Russian economy is going to tank.

We will also see an economic crisis in Europe. The European and Russian economies were closely intertwined. As a result, we have lots of losers in the situation. This probably includes a long-term division of Ukraine, as far as we can tell, but of course, much depends on how the Russians fare on the battlefield. They have not done so well so far due to the unexpectedly strong resistance by the Ukrainians to Russian aggression.

From openDemocracy