Dr Robert Dalsjö, from the Swedish Defence Research Establishment (FOI), laid out Deterrence by Punishment as a concept. Dalsjö argued that most small European states today have armed forces that are too small to realistically pursue denial strategies. At the same time, the proliferation of cheap and widely available precision-strike capabilities have made most states more vulnerable, given that it is very hard to defend against such weaponry. Since defence is difficult, the solution could be to emphasise the counter-attack by acquiring a secure, survivable conventional second-strike capability.
Such a capability would deny the aggressor the ability to conduct the conflict on his chosen terms, enable the counter-attacker to choose time, place and means, and to hit the enemy's vulnerabilities. These strikes could be calibrated for PR-effect. Using such a second-strike capability could also allow the defender to escalate the conflict in order to internationalise it, drawing in allies and partners. Finally, the second-strike capability would be a useful tool for signalling and countering bullying.
Dr Ian Bowers, from the Norwegian Institute for Defence Studies (IFS), argued the case for Deterrence by Denial. Bowers argued that deterrence by denial strategies are inherently less risky for small states than one based on punishment, and denial complemented strategies based on extended deterrence. In essence, deterrence by denial aims to maintain capabilities that will reduce the benefits of any attack and ensure that an aggressive act will ultimately have negative results, thereby reducing the likelihood of an actor committing an aggressive act. Denial is therefore ultimately about making a war of aggression undesirable.
Small states can aim to achieve deterrence by denial by having a force structure and operational approach that aims to prolong a war and deny the enemy the ability to achieve a quick victory. In-place forces needed for denial can both deny an opponent a quick fait accompli and act as a tripwire triggering allied involvement. At the core of a denial strategy is to either convince an opponent that the small state can prevent it from achieving its objectives or make achieving its objectives particularly difficult. Deterrence by denial arguably has a stronger complementary relationship with extended deterrence than its punishment counterpart. For a small state, it is politically important to keep the fight going, as it is politically easier to assist an ally that is still fighting as opposed to justifying undertaking offensive action to restore your ally's territory. Denial is, however normally considered an expensive military strategy, requiring substantial ground and air forces.
Finally, Dr Stephanie Pezard, of the RAND Corporation, outlined Extended Deterrence. Pezard argued that extended deterrence is particularly attractive for small countries since it offsets the power disparity with a larger challenger. However, it is also inherently more complicated than regular deterrence, given that it involves a triangular relationship which opens up the possibility of differences of perceptions between not only the defender and the aggressor, but also the defender and its ally. This triangular relationship makes it more difficult to assess the strength of deterrence and makes credibility issues more pronounced. For example: to what extent does deterrence apply to gray zone threats?
Successful extended deterrence requires not only a strong alliance, but also the perception by the challenger that the alliance is strong. The defender can communicate its intention to protect its protégé in various ways, including by publicizing commitments, displaying joint forces and developing credible flexible response options. Pezard emphasized that it could generally be a good idea to be precise about the threshold which would trigger intervention but more vague about the exact response which would follow. This would give the larger ally more room to maneuver when responding to aggression. As far as "gray zone" issues is concerned, such as cyberattacks, she argued being vague had advantages. It could trigger an Article 5 response in NATO, making a challenger wary of crossing a threshold by mistake and facing retaliation from a more powerful adversary.
The subsequent debate centered upon the inherent risks involved in a deterrence by punishment strategy, the approach most different from the "traditional" small state approach to deterrence, but also the realism in pursuing a more traditional deterrence strategy in today's day and age.