Thus, targeted contracts ensure security of supply without jeopardizing the objective to achieve the economic benefits of well-functioning energy only markets in the longer run. The advantages of such targeted contracts are their rapidity and simplicity, and that they can be transitory. In markets without locational signals but facing recurrent congestion or a voltage stability problem, system operators usually force the operation of plants, even when their cost is higher. In general, such actions are necessary with older plants that are less efficient.