Meaning: Satellites can be used by the armed forces for various reasons.
Choice of Words: Military means something is related to the armed forces. Purposes are the reasons why something is done.
Alternative Expressions
Satellites are helpful tools for the military.
Meaning: This sentence means that satellites are useful objects that can help the military in their work.
Choice of Words: **Helpful** means something that is useful or beneficial. **Tools** are objects that are used to do a job. In this sentence, **tools** refers to the satellites.
The military uses satellites for many different tasks.
Meaning: This sentence means that the military uses satellites to do many different jobs, such as communication, navigation, and weather forecasting.
Choice of Words: **Tasks** are jobs or duties that need to be done. In this sentence, **tasks** refers to the different ways that the military uses satellites.