Energy security is commonly defined as the availability of reliable supplies at affordable prices. From the perspective of the political decision-makers of the exporting countries, energy security means the guarantee of reliable revenues from their final markets. This guarantee is of paramount importance where the revenues are fundamental for the decision-makers in order to gain support for the political system.
Exporting countries face two types of risk: physical and economic. Physical risk concerns the material possibility of exporting the energy resources. Therefore, it primarily refers to the (the lack of) military control of the territory (or, at least, of the production and transport infrastructures) and to the protection against terrorism. Economic risk refers to the amount of revenues: if the prices plummet, public expenditure cannot be sustained and political instability could arise; if the prices rise quickly or unpredictably, short run revenues skyrocket, but in the long run importing countries become more efficient and diversify their energy mix, compromising future revenues (and stability).