This question is timely and intrinsically linked to how we react to Moscow’s current (outlandish) proposals. But first, one has to distinguish between the deterrence debate and the diplomatic practice. Of course, they are closely linked.

Deterrence is a way to communicate intent and resist facing potentially aggressive behaviour. It is a show of determination not to yield to pressure and, if needed, to up the ante. It shows why No Fist Use and Sole Purpose concepts are wrong – These give a potential attacker the monopoly to threaten nuclear use, giving an advantage in a confrontation.

On the diplomatic level, dialogue is not a preface to yield concessions to an adversary, as some allies may believe. The point is to show a national position that may be more convincing than a unified response, potentially muddled through the need for consensus.

But it has been a mistake for allies to refuse to engage with Russia following the 2014 invasion of Crimea and suspension of the NATO-Russia dialogue. The issue has been a lack of confidence from some on the convergence of dialogue at and in the NATO-Russia council.

Does this public show of nuances between allies weaken its deterrent position in Moscow’s eyes? One has to consider the cost of such diplomatic rigidity and the message this sends. 1) reinforces convictions that NATO is a tool of the US, (b) European interests are secondary (see the Trump experience), and (c) makes Moscow well aware and able to play off nuances between allies (see Turkey).

Benoit D’Aboville, Former Ambassador and Permanent Representative to NATO, Vice President of the Fondation pour la Recherche Stratégique, France

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There were periods during the Cold War when effective deterrence was achieved without dialogue. One such period followed the Russian shooting down of a Korean airliner. But more often, deterrence worked best when dialogue, for example over arms control or over what became known as the Helsinki Accords , were under active negotiation, placing less exclusive weight on military deterrence. And the Cuban Missile Crisis in its opening stages showed just how dangerous the absence of dialogue could be.

During the last few years, since the latter part of the Obama presidency and throughout President Trump’s term of office, there was no dialogue worthy of the name. That did not work well in reducing the risk of miscalculation. So all the more welcome were the first, very tentative green shoots of dialogue emerging from the Geneva meeting this week between the US and Russian Foreign Ministers.

But dialogue without credible deterrence does not work well either. So all the more reason to strengthen deterrence as an essential condition for successful dialogue.

Lord David Hannay, Former Ambassador to the United Nations and European Community, Member of the House of Lords, United Kingdom

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With the massive build-up of Russian military forces and equipment near the Ukrainian border, European security is once again called into question. There is a real danger of an armed conflict in the middle of Europe.

The response of the EU, NATO and the G7 has been clear and unanimous: military aggression against Ukraine would be met with massive consequences. But yet, deterrence alone will never be able to end confrontation, build up trust, and create a durable way forward. There is, and there can be, no alternative to dialogue.

Dialogue initiatives such as the CSCE and the resulting Helsinki Accords have laid the foundation for the existing security architecture in Europe. Without dialogue, there can be no lasting security. It is therefore good news that the NATO-Russia Council recently convened for the first time in two and a half years.

Foreign minister Baerbock’s talks in Moscow in which she called for reinvigorating the Normandy format have been another important step to open up room for dialogue and negotiations.

At the same time, it is clear that dialogue needs to be underpinned by instruments capable of discouraging a military escalation. Whatever form or scale these instruments may take, European unity and strong transatlantic cooperation are essential to maximize their clout.

Dialogue and deterrence need to go hand in hand. But in order to strengthen European security, a third factor is indispensable: reinforcing disarmament initiatives.

The suspension of important arms control treaties and confidence-building measures such as the INF treaty and the Treaty on Open Skies have significantly increased the danger of misunderstanding and military escalation. We have to reverse this worrying trend.

As utopian as it may sound in these dire circumstances: Our goal must be a nuclear-free world. It is no law of nature that dialogue must always be accompanied by deterrence. The P5 rightly reiterated at the beginning of this year: A nuclear war cannot be won and must never be fought. The higher the tensions are, the more important this aim becomes.

 Katja Keul, Minister of State, Federal Foreign Office, Germany

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This is a difficult question. A better one might be, “can deterrence be made safe without dialogue?”

In Stanley Kubrick’s masterpiece, Dr Strangelove remarks that the whole point of having a Doomsday Machine is lost if it is kept a secret. You cannot deter someone from taking a specific action without communicating, in some way, what the consequences would be. But communication is not dialogue.

In classical deterrence theory, this is expressed as a general need for punishment being swift, certain and severe for it to be effective. As applied to nuclear deterrence, the severity of a nuclear strike is beyond doubt, but what about the other two elements? For instance, nuclear weapons would lose most of their deterrent effect if the opponent does not believe that you would have the resolve to use them.

You would need to communicate both your capability and intent to the person or entity you would seek to deter, and you would need to do so credibly. You would also want to dissuade your opponent from thinking that the threshold of nuclear use is too low, as this might bring pre-emptive strikes onto the table in times of tension. Nuclear possessor states can only do this through some form of exchange of positions and views. An example would be the discussion on doctrines that is taking place within the so-called P5 process.

For sure, deterrence cannot exist without communication, and only dialogue can reduce the risks of this practice, rendering it effective.

Andreas Persbo, ELN Research Director, Sweden

The opinions articulated above represent the views of the author(s) and do not necessarily reflect the position of the European Leadership Network or any of its members. The ELN’s aim is to encourage debates that will help develop Europe’s capacity to address the pressing foreign, defence, and security policy challenges of our time.