What is the primary mission of the RC-135U (Combat Sent)?

The primary mission of the RC-135U (Combat Sent) is to gather electronic intelligence data. This specialized aircraft is designed to intercept and analyze electronic signals from enemy systems, which can include radar and communication transmissions. This capability is crucial for understanding adversary capabilities, intentions, and actions, making the RC-135U an integral part of strategic intelligence efforts.

The other options relate to different types of intelligence collection that are not the main focus of the RC-135U. For instance, imagery intelligence involves collecting and analyzing visual images, primarily from satellite or aerial photography, which is not the core function of the RC-135U. Similarly, while communications intelligence is a significant component of electronic intelligence, the RC-135U's primary aim is broader, encompassing a wider range of electronic signals. Lastly, monitoring naval operations pertains to maritime intelligence, which is outside the specific role that the RC-135U fulfills in the realm of air and electronic surveillance.