As the war in Ukraine rages, perhaps the most globally significant event since it started has been the Russian president's declaration that his country’s nuclear arsenal has been put on a special "combat-duty regime". As intimidation tactics go, it’s hard to trump. But how worried should the world be by Putin playing the nuclear card? Claire Byrne wanted to find this out when she spoke to Dr Pavel Podvic, Senior Researcher in the Weapons of Mass Destruction and Other Strategic Weapons Programme at the United Nations Institute for Disarmament Research in Geneva. Claire started by asking him whatever happened to nuclear disarmament?

"A lot of things have been done. We came down – and by we, I mean the United States and Russia – from arsenals of about 35-40,000 weapons, to arsenals of about 4,500 weapons. But then politics intervened."

People clung onto their weapons, Dr Podvic says, in the hopes of bringing stability and predictability. Unfortunately, as we can see now in Ukraine, neither stability or predictability have been much in evidence. Now Putin is using his nuclear arsenal as the ultimate deterrent:

"That’s more or less how deterrence is supposed to work. It’s exactly the threat of using nuclear weapons is supposed to prevent people from doing certain things. But what we see today is that, yes, Russia is using its nuclear weapons to basically cover its actions in Ukraine and unfortunately again, as we can see, we ended up in the worst of all worlds."

It’s estimated, Claire says, that Russia has the greatest number of nuclear weapons at around 4,500. But is that number verifiable?

"Not really. These are estimates and Russia has never disclosed officially the size of its arsenal. But these numbers could be reasonably well guessed and at some level it doesn’t matter whether it’s 4,500 or 5,000."

Given the setbacks that Russian forces have suffered on the ground in Ukraine, it appears that they might not be the well-oiled elite military machine that we thought they were. Claire wonders if maybe we might assume the Russian nuclear arsenal is also not what we thought it was. Dr Podvic is not convinced:

"I would not do that, for a variety of reasons, the main one being that even one weapon would basically spoil your day. These are very dangerous, very powerful weapons in many ways. And even if it’s just a fraction of the arsenal, they will bring devastating consequences."

What about President Putin putting his nuclear deterrent forces on high alert? Is Dr Podvic worried about that?

"On one level, I do not believe that this announcement indicates an aggressive intent, an intent to use [nuclear] weapons actively in this conflict, but on the other hand, I worry that the very fact that the Russian president brought nuclear weapons into this conflict, put them on the table, I think this is quite dangerous."

Dr Podvic believes that the international community should take a very strong stance against any potential use of nuclear weapons in this – or any – conflict. But Claire wants to know if Dr Podvic believes Putin would use his nuclear arsenal in this campaign. The answer she gets isn’t entirely reassuring:

"Well, as I said, I don’t believe that Russia has an aggressive intent to use these weapons pre-emptively. On the other hand, I firmly believed the invasion would not happen because this is a move that makes absolutely no sense."

Using nuclear weapons also makes absolutely no sense, of course, so we have to hope that Dr Podvic’s belief is right this time.

You can hear Claire’s full conversation with Dr Pavel Podvic by going here.