Although Americans and Europeans differ about why, how, and when coercion is legitimate, it will remain an essential element of liberal democracies’ foreign policy. But, as has been argued before, the record of success is mixed. Failed interventions or partially successful efforts to coerce could undermine the credibility of foreign policy. As interventions usually provoke negative reactions in other countries, failed attempts to coerce an adversary could also jeopardize the stability of international relations. Especially interventions carried out solely for moral and ethical reasons are not always understood in other cultures, and therefore pose considerable challenges. To be successful, coercion could require the decisive use of force. However, states are willing to use force decisively only if vital interests are at stake. Actually, if their vital interests are at stake, liberal democracies have no alternative but to coerce others.

This chapter aims to contribute to the further development of theory. I will first deal with the development in thought that has taken place with respect to the use of power instruments in international relations. Following a description of existing theories, I argue that coercion requires a specific type of decision making, one that is based on a dynamic approach and knowledge about the instruments of power. To this end, I will provide insights into the mechanism that lies at the foundation of coercion and, subsequently, several different strategies that the intervener can use will be presented. The central question is how the instruments of power can be engaged most effectively in order to achieve political objectives. In order to assess the efficacy of power instruments, theoretical insights are required into the mechanism that lies at the foundation of coercion.

In spite of the substantial media interest in interventions in conflicts, academic research into the manner through which force can be used to coerce actors most effectively is marginal. Discouraged by disappointing results, the consensus gradually developed that strategic thought should focus more on the actual use of military force and less on deterrence, conflict prevention, and peace building. Thus, to an increasing extent, the success of military force is to be judged on the basis factual effort.