Final answer:
All aircraft types mentioned in the question, including commercial airliners, military fighter jets, cargo planes, and helicopters, can normally be issued a speed reduction by air traffic control. The ability to comply may differ based on operational requirements or limitations.
Step-by-step explanation:
The question relates to which type of aircraft cannot be issued a speed reduction. Typically, all categories of aircraft, such as commercial airliners, military fighter jets, cargo planes, and helicopters, can be issued a speed reduction by air traffic control (ATC) for a variety of reasons, such as traffic management or safety considerations. However, there may be situations where certain aircraft, particularly military fighter jets, may be unable or unwilling to comply with speed reductions due to operational requirements or the limitations of the aircraft. But, without a specific operational context, all these aircraft types can be issued speed reductions. Hence, the question is ambiguous without additional context.