Sustainment, also known as "obsolescence management" and "DMSMS" (Diminishing Manufacturing Sources and Material Shortages), focuses on the issues surrounding "The loss or impending loss of manufacturers of items or suppliers of items or raw materials."

As a multifaceted problem, sustainment has several dynamics:

• As new products are designed, the technology that was used in their predecessors becomes outdated, making it more difficult to repair the equipment.
• Some parts may be harder to acquire because fewer are produced as the demand for these parts decreases.
• Materials required to manufacture a piece of equipment may no longer be readily available. 

Other obsolescence dynamics include the lack of availability due to:

• Statutory and process changes
• New designs