Which of the following is NOT a Data Terminal Set (DTS) used for Link 11 operations?

The correct answer identifies the AN/USQ-99 as not being a Data Terminal Set (DTS) used specifically for Link 11 operations. The AN/USQ-99 is a tactical data link system primarily designed for Link 16 operations and is not classified as a DTS for Link 11, which is an older communication protocol.

In contrast, the SG-50, MX-512P, and KG-40A are established systems designed for Link 11. The SG-50 is a type of Link 11 DTS that allows for secure tactical communications. The MX-512P is another important DTS that enables Link 11 operations, supporting data reporting and communication among different military units. The KG-40A, while primarily a secure voice equipment, is also part of the Link 11 architecture and facilitates secure communications.

Thus, these three systems are intrinsically linked to the operation and functionalities of Link 11, while the AN/USQ-99 operates in the context of the more advanced Link 16, highlighting the specific roles and capabilities associated with different data link systems in military operations.