In the RMF, what phase follows the selection of security controls?

The phase that follows the selection of security controls in the Risk Management Framework (RMF) is indeed the implementation of those security controls. Once security controls have been selected based on the risk assessment and categorization of the system, the next logical step is to put these controls into action. This involves configuring, deploying, and ensuring that the selected security measures are fully operational and integrated within the system's architecture.

Implementation is crucial because it is during this stage that the effectiveness of the selected controls begins to manifest in reducing risks and protecting the organization's assets and data. This phase lays the groundwork for the subsequent assessment of the controls, meaning that without implementing them first, there would be no basis for evaluating their efficacy.

Other phases, such as assessing or monitoring security controls, occur after implementation, and they focus on evaluating the performance and ongoing efficacy of the controls that have been put in place. These processes are essential for maintaining accountability and ensuring that the security measures remain effective over time, but they cannot commence until the controls have been properly implemented.