What are USAF subdivisions directly subordinate to the Chief of Staff of the Air Force called?

The subdivisions of the United States Air Force (USAF) that are directly subordinate to the Chief of Staff of the Air Force are known as Direct Reporting Units (DRUs). These units have a unique status as they report directly to the Chief of Staff, allowing them to operate independently in their respective missions, but still operate under the broader policies and guidance established by the Air Force leadership.

DRUs are typically created to manage specific functions or responsibilities that do not fall under the typical commands, enabling a focused approach to address operational needs or specialized areas such as training, administrative functions, or equipment management. Their structure allows for flexibility and rapid response to evolving requirements.

The other options pertain to different types of organizational structures within the Air Force that serve distinct purposes. Combatant commands are involved in broad operational commands and joint military operations. Field operating agencies focus on providing specific support and services but may not report directly to the Chief of Staff. Numbered air forces are primarily tasked with organizing, training, and equipping forces for combat and report upwards through major air commands rather than directly to the Chief.