Power is the ability to get others to do what one wants. This can be done in a positive way through encouragement (incentives), or in a negative way through force (coercion). If diplomacy is reinforced with economic sanctions and the threat or limited use of military power, then we call this ‘coercive diplomacy’. During the Ukraine crisis, which will be discussed in Chapter 9, the European Union and the United States attempted to influence President Putin's behaviour by using coercive diplomacy. Strategy is the critical success factor for this. Strategy determines how political aims should be met using instruments of power. For the political aim, what is essential is not to convince one's opponent that they are wrong – after all, this will not work – but to manipulate and influence his politicostrategic choices.

A country has limited options for exercising its power. Economic sanctions and the use of military might are the only instruments to exercise real power. These two instruments thus determine the effectiveness of a country's diplomacy.

In the 18th and 19th centuries, the size of a country's land forces was the most important expression of its power. During the inter-war period, naval capabilities were the most important expression of power. During the Cold War, power was expressed by having massive armed forces and nuclear weapons, which had to deter the opponent from using its armed forces. After the Cold War, a unipolar world emerged and the focus came to lie mainly on GDP. In the West, military might became an instrument for achieving humanitarian objectives, for example.

A study by the American RAND Corporation has established that a country's power is dependent upon three variables: wealth, innovation and conventional military capabilities. 54 Wealth, as expressed by GDP, provides independence, can be used to put pressure on opponents and offers a good starting point for negotiations. Innovation is needed for prosperity and having better military capabilities than potential opponents. It is striking that the RAND study did not identify nuclear weapons as an instrument of power. This is because nuclear weapons cannot or can hardly be used on the battlefield, while their use can lead to mutual destruction.