Which principle of sustainment involves maintaining operations through flexibility and support?

The principle of sustainment that involves maintaining operations through flexibility and support is known as improvisation. This principle is crucial because in military operations, unexpected challenges and changes in the environment can arise at any time. Improvisation allows units to adapt quickly to evolving situations by leveraging available resources, making adjustments as needed, and thinking creatively to solve problems. It emphasizes the importance of being able to operate effectively even when plans do not go as designed, ensuring that mission objectives can still be met despite unforeseen obstacles.

In contrast, the other principles focus on different aspects of sustainment. Economy pertains to the efficient use of resources to maximize effect. Survivability focuses on protecting personnel and equipment. Simplicity emphasizes making plans and operations straightforward to reduce confusion and increase effectiveness. While all of these are vital for successful military operations, improvisation specifically addresses the need for flexibility and support in sustaining operations amidst uncertainty.